Luminous Landscape Forum
Raw & Post Processing, Printing => Printing: Printers, Papers and Inks => Topic started by: Mark Lindquist on April 21, 2016, 08:14:47 am
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So we all know that once a substrate is printed, that the print needs to "dry down" as the ink becomes absorbed by the paper, particularly matte paper. During this 24-48 hour waiting period, remarkable changes take place. I surmise that the ink is cominglling with the fibres of the print and the water has to evaporate. Then there is off-gassing.
So what's up with this? Are the ink molecules and paper fibre molecules rearranging, then finally settling down, or is it just as simple as water evaporating?
Different rates of absorbtion for different papers. What's really going on here? This phenomenon is easy to observe, but not so easy to fully understand.
Mark
Spelling syntax edits
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As far as I understand the process, the substrate is the base, and the ink is absorbed onto and in the coating. The main change that occurs is the off-gassing, during which there is some evaporation of the gasses released from the ink once it is sprayed onto the coating. Whether more profound chemical changes occur that also cause a visible difference of print appearance a day later I do not know. With today's high quality papers and inks, drying is very rapid, but the printed surface isn't fully hardened till 12 hours or so after printing.
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So we all know that once a substrate is printed, that the print needs to "dry down" as the ink becomes absorbed by the paper...
Unlike what happens in the wet darkroom, my understanding is that inkjet prints actually "dry up" very slightly rather than "dry down." In other words, the print will be very slightly darker when it first comes off the printer compared to later after it has dried. I've never actually measured this, but I think I've seen it visually, especially in the darker areas of the print. I'm sure this probably varies (maybe a lot) depending on the ink and paper being used.
Dave
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So we all know that once a substrate is printed, that the print needs to "dry down" as the ink becomes absorbed by the paper, particularly matte paper. During this 24-48 hour waiting period, remarkable changes take place. I surmise that the ink is cominglling with the fibres of the print and the water has to evaporate. Then there is off-gassing.
So what's up with this? Are the ink molecules and paper fibre molecules rearranging, then finally settling down, or is it just as simple as water evaporating?
Different rates of absorbtion for different papers. What's really going on here? This phenomenon is easy to observe, but not so easy to fully understand.
Mark
Spelling syntax edits
In most papers, the ink doesn't actually reach the fibres. If you look at the cross-section of printed inkjet paper under a microscope, all the pigment is in the upper layers of the microporous layer (which is behind a glossy polymer layer for gloss papers, or on the very surface for matte papers). The carrier fluid reaches the paper base, unless there's a RC layer in the way (not sure if it can soak through baryta layers) but doesn't enter the paper fibres themselves, since they are both internally and externally sized. It just sits in the pores between the fibres, held there by surface tension, until it can evaporate; if it did actually soak into the fibres, it would cause dimensional change, which clearly doesn't happen.
Different rates of absorption is pretty easy to explain - different microporous layers have different affinities for the different carrier fluids and encapsulation resins, while paper bases have different levels of porosity and use a number of different external sizing compounds (gelatin, PVA, etc.) which each have different affinities for water molecules.
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I should have said "with fine art Matte Papers", where this effect is most pronounced.
I found this graphic regarding Fine Art Inkjet Paper from Rochester Institute of Technology, and it appears that the ink could go into the paper somewhat, in the absence of an RC layer. It would make sense that the ink could migrate and "Key" into the uppermost paper fibers without warping the paper.
In my experience, and I print a great deal, this phenomenon is clearly visible. The print comes out, it is relatively dull and lifeless, but by 24 hours it is fully in a finished state, looking most like the image on the monitor.
I believe this happens mostly on Matte papers as instant dry papers and RC coatings pretty much give instant results.
No doubt this is entirely dependent upon which paper is being used, but I was hoping to learn of a name for the phenomenon and get additional information about it, not necessarily anecdotal.
Thanks for your replies - much appreciated.
Mark
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I should have said "with fine art Matte Papers", where this effect is most pronounced.
I found this graphic regarding Fine Art Inkjet Paper from Rochester Institute of Technology, and it appears that the ink could go into the paper somewhat, in the absence of an RC layer. It would make sense that the ink could migrate and "Key" into the uppermost paper fibers without warping the paper.
In my experience, and I print a great deal, this phenomenon is clearly visible. The print comes out, it is relatively dull and lifeless, but by 24 hours it is fully in a finished state, looking most like the image on the monitor.
I believe this happens mostly on Matte papers as instant dry papers and RC coatings pretty much give instant results.
No doubt this is entirely dependent upon which paper is being used, but I was hoping to learn of a name for the phenomenon and get additional information about it, not necessarily anecdotal.
Thanks for your replies - much appreciated.
Mark
It takes a fair bit of ink for the pigment to reach the base layer. The microporous layer has a huge surface area for the adsorption of pigment particles. If it does, it's probably over-inked - don't forget, if it reaches the base layer, it will start to run along the fibres and you'll get increased dot gain and feathering (unless it's a rare paper where the paper sizing itself is designed to be inkjet-receptive, or if you're mitigating it with a platen heater to accelerate evaporation).
I suspect the change in appearance has little to do with changes in the pigment or ink itself and a lot to do with changes in the base layer. After all, the encapsulated pigments are designed to change as little as possible and be as unreactive as possible - anything else would be bad for longevity.
Consider how colour as visualised is generated by a print. You have incoming white light. A good ink is translucent - it needs to strongly absorb all visible-light wavelengths except the colour you want the ink to be (i.e. for a blue ink, you'd want the pigment to be transparent to blue light, but strongly absorb all other wavelengths) and the particles need to be small enough to minimise reflection, which will scatter the light and reduce saturation and contrast (the exception is black ink, which should be as opaque as possible and whose particles should absorb as much visible-spectrum light as possible, and white inks designed to be able to print a base layer, which should also be as opaque as possible). The light passes through the ink layer, with the wavelengths corresponding to the ink colour passing through and other wavelengths being filtered out. It is then reflected off the opaque layer behind the ink - a baryta layer, RC layer or the paper base - passes through the ink layer again (i.e. being filtered a second time, further increasing the proportion of remaining light of the desired wavelength and, thus, increasing the saturation) before reaching the eye and being interpreted as colour.
Seems simple enough - and it is. But consider what happens to the paper base as you print. Aqueous ink is mostly water, together with some other solvents. When it passes through the microporous layer, it is absorbed by the paper base - the very layer you're relying on to reflect light. What does saturated paper look like? Just dunk a piece in the basin and see for yourself. It reflects less light than dry paper, appearing greyish rather than white. The specularity of its reflections also changes. Effectively, a fresh print is ink in front of grey paper, not white. That's why colours look dull and muddy. As the paper base dries, it becomes white again and the colours appear vibrant. The ink hasn't changed, but the backdrop has. This also explains why RC papers and baryta papers don't exhibit the same degree of change as the print dries - the background, off which light passing through the ink layer is reflected, doesn't change as much when wet, if it changes at all.
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Now that's an excellent interpretation and explanation. Appreciate it Doc!
Mark
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It is my understanding that in coating most papers for inkjet printing, a barrier coating is put down on the raw paper base first, followed by the microporous inkjet receiver layer. The printed ink should mostly get absorbed by the microporous layer. If you are "over inking", some of the ink will lay on top and dry. This could lead to loss of d-max. In "double printing" tests many years ago, we observed that laying down 2 applications of black in an effort to increase d-max had the opposite effect. We developed an target for printing, to maximize d-max results.
John Nollendorfs
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It is my understanding that in coating most papers for inkjet printing, a barrier coating is put down on the raw paper base first, followed by the microporous inkjet receiver layer. The printed ink should mostly get absorbed by the microporous layer. If you are "over inking", some of the ink will lay on top and dry. This could lead to loss of d-max. In "double printing" tests many years ago, we observed that laying down 2 applications of black in an effort to increase d-max had the opposite effect. We developed an target for printing, to maximize d-max results.
John Nollendorfs
Baryta layers and RC papers have this barrier layer. That's why they take longer to outgas. Most matte papers do not - the carrier fluid goes straight through into the paper base, air can do the same (so they take less time to outgas) and it also becomes possible to apply laminates that soak right through into the paper base.
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Baryta layers and RC papers have this barrier layer. That's why they take longer to outgas. Most matte papers do not - the carrier fluid goes straight through into the paper base, air can do the same (so they take less time to outgas) and it also becomes possible to apply laminates that soak right through into the paper base.
I doubt that. Hahnemühle has 3 coating layers applied by Sihl on their best matte art papers. The trick is to pull out the ink fluids fast after a droplet lands on the surface and have the pigment fixed at the surface front, not going deeper or sideways. After that evaporation of the ink fluids should start. So a build up on the paper base of a barrier, fast absorber, top coating is likely. A barrier on the paper base acts more like a membrane then, think Goretex, it blocks fluids but does not block gasses, steam etc.
It could even be a difference in the particle size of the inkjet coating minerals that changes the pore sizes going deepr into the coating layer. Mitsubishi usually gives more details:
https://www.mpm.co.jp/eng/rd/field/inkjet.html
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2016 update, 700+ inkjet media white spectral plots
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I doubt that. Hahnemühle has 3 coating layers applied by Sihl on their best matte art papers. The trick is to pull out the ink fluids fast after a droplet lands on the surface and have the pigment fixed at the surface front, not going deeper or sideways. After that evaporation of the ink fluids should start. So a build up on the paper base of a barrier, fast absorber, top coating is likely. A barrier on the paper base acts more like a membrane then, think Goretex, it blocks fluids but does not block gasses, steam etc.
It could even be a difference in the particle size of the inkjet coating minerals that changes the pore sizes going deepr into the coating layer. Mitsubishi usually gives more details:
https://www.mpm.co.jp/eng/rd/field/inkjet.html
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2016 update, 700+ inkjet media white spectral plots
Multiple layers, certainly. But not necessarily a barrier layer. What the coating needs to do is separate the pigment from the carrier fluid as quickly as possible (keeping the pigment particles on or near the surface, or immediately behind a transparent top coat), and the quickest way out for the fluid is into the paper. Put a liquid-impervious barrier there and the ink on the surface takes longer to dry.
Matte papers do not appear to have a top coat in front of the pigment. I suspect any kind of effective top coating would change the surface appearance of the paper, generally making it glossy, and have pores too small to allow matte black pigments to pass through (instead, you can apply a top coating to matte paper with a protective spray afterwards). Glossy papers almost universally have such a layer.
Obviously, the main job of separating the pigment from the carrier fluid is done by the microporous layer. This has a large surface area to allow for the adsorption of pigment particles, as well as high porosity to allow fluids and gases to pass through quickly. The layer holding the pigment also needs to be transparent to light.
Yes, some matte papers will have multiple coatings. But I do not believe a barrier layer is one of them. It seems more likely that the extra layers would be several different microporous layers - the topmost layer being a transparent microporous layer to separate out the pigment, and deeper layers designed either to hasten the passage of fluid into the paper base (allowing a greater ink load), increase whiteness (and hide some of the paper texture) by using a pigmented microporous layer or help separate out the other, non-water components of the carrier fluid (glycerine, etc.) so that they remain closer to the surface and outgas faster than if they penetrated all the way into the paper base.
You can demonstrate the lack of a barrier layer in many papers using a method I've been using for a number of years to protect and change the surface characteristics of matte paper. Dilute some Timeless with water (4 parts Timeless to 1 part water; you can also add a drop of Photo-Flo to aid wetting). Spray it on the paper and allow it to soak in. Once it's dry, cut through a cross-section of the sprayed paper. You will find that the Timeless has penetrated deep into the paper base, binding the ink receptive layer and the paper fibres into a single, solid mass of ink, Timeless and paper that can't flake or delaminate. If there were a barrier layer preventing fluid penetration, this would not be possible - and it doesn't work on most glossy or baryta papers.
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I doubt that the best paper companies freely share their formulas and processes.
At the very least, the layering of barriers and or bases is combinatorial and involves semi-permeable membranes. I still contend that anchoring to paper fibres in matte papers is a requisite condition that contributes to the greater depth that the best of these papers exhibit. Otherwise, why then would there be the distinctions between papers based soley on their coatings?
Back to my main topic which is the drying time of the ink and carrier fluids. In a particular case, with the HP Z3200ps printer using Epson Ultra Smooth Fine Art Paper, and using a custom made profile based on the paper preset: Fine Art Paper More Ink, which employs Quad Inks, (PK,MK,G, and LT G) and indicates the total amouny of ink emplyed to maximize gamut without causing image quality problems. In general, the higher the ink limit, the higher the gamut. In general, the ink limit setting for Quad inks is 60 and is applied unidirectionally only.
So, a greater amount of ink is laid down along with a significantly greater carrier. In my view it follows that the receptor coatings on matte papers must be predominently semi permeable filtering membranes to enable water, glycerin, (combinatorials) to flow through the ink receptors, barriers, etc., into the paper fibers at uppermost levels in particular to prevent puddling. Evidence of this is when a print is made on a thinner yet sturdy fine art paper such as Canon Premier Matte Pro, that the paper is weighty in the hand and somewhat limp as in water-logged. It follows that the excess or bound water must evaporate either from the front or from the back. I contend that as the carriers and chemicals dry, the ink sets, having a bond with the paper (this not unlike shadowblade's excellent example), and cures, albeit slowly to a harder surface. In so doing, the result is lighter and clearer, whith greater depth. I've observed that a gloss print will also exhibit these tendencies although at an excelerated speed. One thing discussed is the fact that any target which is measured within minutes of printing will be innacurate. Apparently not so much so, however, that the resulting measurements are not at least in the ball park.
Knowing what I do about staining and finishing wood, I have an intuition that the combinatorial elements of the fibers, membranes, filters and surface receptors all play a majpr part in this phenomenonolical aspect of ink drying which can not be merely serendipitous. The color scientists and teams that work in concert to present their paper offerings are too extraordinarily brilliant for that to happen.
EDIT: Syntax, spelling
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Regarding my post about a "barrier layer", it's being taken too literally as a total moisture barrier. When ink jet papers are being coated, you need a base layer, commonly known as a "barrier" layer put down first to prepare the paper surface for subsequent coatings. Most inkjet papers have a number of coatings applied. There are several different ink jet receptor coatings also. Most common, today is the microporous receptor layer. In the early days of inkjet, attempts were made to print on all kinds of art papers. The most successful ones were "tub sized" papers using gelatin, most notably, Arches. (remember all traditional photo papers were coated with gelatin?) From this, modern ink jet paper coatings evolved. In any event, it is not desirable for the ink to penetrate into the base paper at all. As has been noted, the spectral qualities of ink jet ink come from the very top of the microporous layer. As ink drys, of course the image is subject to changes, just as a "wet pet rock" looks much different when it is viewed dry. (pardon the pet rock analogy)
The coatings are designed to prevent the "spread" of the ink droplet, preserving the small droplet size, and purity of the color.
Modern OEM pigmented ink has incorporated dispersants which function to keep the pigments from clumping and settling. They also have a "coating" agent like a polymer, that keeps the pigments strands separated, and also tends to create a contrasty look to the pigments (wet rock look), that enhances the d-max.
The water portion of the ink evaporates rather quickly, as has been noted. What takes longest, are the glycols, which can form a negative image film on a close-by glass surface. Most of the "dry down" is within 24 hours depending on ambient conditions. The glycols of course take much longer.
John Nollendorfs
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Here is an earlier 2012 thread where Ernst Dinkla explains about inks and coatings:
Inkjet Coatings (http://forum.luminous-landscape.com/index.php?topic=62842.0)
Everyone is saying that the ink does NOT penetrate in to the paper fibres at all but I disagree.
There is too much literature and information out there that supports my "key" theory.
Even Epson's own literature illustrates not just the difference between dye and pigment inks but clearly shows that some pigment particles do penetrate near the surface of the paper. I have seen this in a lot of literature. It only makes sense. Some of the ink must go into the topmost layer of the fibers in order to anchor and provide a more stable reflective base. Again, I ask, why would there even be different types of papers if all they did was to provide support for coatings.
I contend that the paper fibers, particularly at their upper most level are involved in this complex equation.
If all the paper did was provide a support for the coatings, then we should have one universal base that is the most stable and simply carries the coatings and served as a universal substrate.
Look at Epson's own graphic illustration attached - doesn't it indicate it and explain it?
In the case of instant dry papers, gloss, semi-gloss, satin, barytes, etc., then yes, I agree the ink does stay confined within the surface layers.
I have a suspicion that for Matte papers, not so.
Until a scientist who actually works on these issues can prove to me definitively that I'm wrong, then I will stick to my opinion.
Mark
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This paper may be of interest to the topic:
Printability and Ink Coating Interactions (http://scitech.stou.ac.th/UploadedFile/Inkjet%20FULLTEXT01.pdf)
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This paper may be of interest to the topic:
Printability and Ink Coating Interactions (http://scitech.stou.ac.th/UploadedFile/Inkjet%20FULLTEXT01.pdf)
That's an amazing paper Mark, thank you for providing that link.
A few interesting aspects:
4.5 Summary
Figure 28. Line width on PVOH-silica coatings with additives.
PVOH-coated samples all presented an excellent colour gamut, which is likely as a result of good film-forming capabilities. The sharpness was also good; however, the coatings suffered from high gloss variation and slow ink drying. With the addition of pigment, a new structure is formed with large pores in and between the pigments, and a macro-roughness generated by the large particles. The inkjet droplets can quickly penetrate into the large pores, and the time for surface wicking is reduced, which is beneficial for the blurriness. However, the macro-roughness promotes bulk spreading in the coarse surface structure; this tends to increase the line width. Finally, the ink ends up within the coating and the colourant is partly shielded by the particles; this reduces the gamut area to some extent. Additives such as cationic polymers and PVP can further improve the print quality. The addition of a cationic additive showed an overall positive effect of gamut area. However, it did not always prevent lateral ink spreading. It is suggested that blurriness is a surface wicking that is greatly determined by the micro-structure of the substrate [82], while line width is a bulk spreading that is promoted by a hydrophilic substrate and perhaps also by a slow absorption by the underlying substrate and/or ink.
Additionally, the paper is dealing most specifically on coatings presumably applying to papers such as gloss, semi-gloss, etc., where even still they are subject to micro-cracks whereby ink can escape through.
Also,
"...The purpose of this work has been to gain an increased knowledge of the mechanisms that con- trol the absorption and the fixation of inkjet droplets on coated papers. The focus has been on printability aspects of high quality (although not photographic quality) laboratory coated inkjet papers for printers using aqueous-based inks. Coating colours, made from a wide range of com- mercial, as well as non-commercial coating chemicals, have been evaluated mainly in terms of inkjet printability and runnability. Print quality aspects, such as line expansion, blurriness, and colour gamut were analysed and correlated to structural features of the coating layer, as well as to ink composition. It was determined that coatings with pure polymer binders gave an excellent colour gamut and that, with an addition of mesoporous pigments, the print sharpness improved. Moreover, it was also determined that the printability and the binder demand were affected by the pore size, as well as pore size distribution of the pigments...."
The fine art matte papers I'm referring to have unique properties not covered in this study. Yet the principles are there. It appears that chemical composition of the coatings in conjunction with the chemical composition of the inks create the interactions which affect color gamut and all other print quality aspects.
Unfortunately, the study did not delve into the properties and qualities of base components of specific papers.
But definitely an eye-opener for sure. Now if you could find a study on the reactivity of paper substrates to high quality aqueous ink jet coatings, inks and drying times, I would be thrilled.
Thanks again.
Mark
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That's an amazing paper Mark, thank you for providing that link.
................ Now if you could find a study on the reactivity of paper substrates to high quality aqueous ink jet coatings, inks and drying times, I would be thrilled.
Thanks again.
Mark
Google is your friend.
But so far I have not found exactly what you are looking for. The one attached may provide some further insight. The subject matter quickly gets very technical and presumes specialist knowledge of the various chemical components entering into the coatings, barriers and the substrates. I think this is a rather deep subject. :-)
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Google is your friend.
But so far I have not found exactly what you are looking for. The one attached may provide some further insight. The subject matter quickly gets very technical and presumes specialist knowledge of the various chemical components entering into the coatings, barriers and the substrates. I think this is a rather deep subject. :-)
Yes I use "The Google" a lot, Mark. Thank you for taking the time to find this article. It is a bit deep, but it's certainly not out of the realm of comprehension or even basic understanding.
An interesting quote found from the paper:
"...It has been speculated that the ink penetrates further into the paper due to the hydrophilic nature of the filler [14]..."
Apparently, depending on the lesser or greater use of ColorLok®, the degree to which ink absorbrption by the paper is tunable and controllable.
Also..."...The main purpose of the work was to improve the physical paper-properties such as cockle and waviness without reducing the print quality. This introduction study deals with the effects of paper properties on print quality...."
This article does shed some light, and it is the closest to come near the question of whether the ink does in fact bind with the paper fibre.
To a degree it apparently does, but is prevented more for purposes of controlling flatness - buckling/warping, etc.
Thanks again, I appreciate your unbiased response to the question at hand.
Mark
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Yes I use "The Google" a lot, Mark. Thank you for taking the time to find this article. It is a bit deep, but it's certainly not out of the realm of comprehension or even basic understanding.
An interesting quote found from the paper:
"...It has been speculated that the ink penetrates further into the paper due to the hydrophilic nature of the filler [14]..."
Apparently, depending on the lesser or greater use of ColorLok®, the degree to which ink absorbrption by the paper is tunable and controllable.
Also..."...The main purpose of the work was to improve the physical paper-properties such as cockle and waviness without reducing the print quality. This introduction study deals with the effects of paper properties on print quality...."
This article does shed some light, and it is the closest to come near the question of whether the ink does in fact bind with the paper fibre.
To a degree it apparently does, but is prevented more for purposes of controlling flatness - buckling/warping, etc.
Thanks again, I appreciate your unbiased response to the question at hand.
Mark
'Ink' means more than one thing here. It can refer to the whole thing - pigment, carrier fluid and all - but it can also refer to the carrier fluid alone, which is part of the ink and, undoubtedly, reaches the paper base.
As to whether the pigment reaches the paper base, that really depends how much ink you're putting onto the paper.
Look at a cross-section through an ink dot on a piece of printed paper. The dot is widest at the very surface, becoming narrower and narrower deeper into the layer, essentially forming a hemi-lenticular shape. That is, the more ink is placed on a particular point on the surface at the same time, the deeper the pigment goes. If you put enough ink on the same spot, some of it will reach he substrate. If that happens, that part of the coating has been over-inked - once it reaches the base, it spreads along paper fibres just as on uncoated papers.
So, yes, pigment can reach the substrate, if you dump enough ink on it. But, if the paper is profiled correctly, it shouldn't. And you wouldn't want it to - if it reaches the substrate, it's free to spread in the same manner as on uncoated paper, increasing dot grain and decreasing resolution.
HP's Color-Lok technology is unrelated - it improves the performance of uncoated papers, not coated ones. Effectively, it's a different form of external sizing for the paper, giving the sizing some of the properties of an inkjet-receptive layer to prevent pigment migration along the fibres.
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'Ink' means more than one thing here. It can refer to the whole thing - pigment, carrier fluid and all - but it can also refer to the carrier fluid alone, which is part of the ink and, undoubtedly, reaches the paper base.
As to whether the pigment reaches the paper base, that really depends how much ink you're putting onto the paper.
Look at a cross-section through an ink dot on a piece of printed paper. The dot is widest at the very surface, becoming narrower and narrower deeper into the layer, essentially forming a hemi-lenticular shape. That is, the more ink is placed on a particular point on the surface at the same time, the deeper the pigment goes. If you put enough ink on the same spot, some of it will reach he substrate. If that happens, that part of the coating has been over-inked - once it reaches the base, it spreads along paper fibres just as on uncoated papers.
So, yes, pigment can reach the substrate, if you dump enough ink on it. But, if the paper is profiled correctly, it shouldn't. And you wouldn't want it to - if it reaches the substrate, it's free to spread in the same manner as on uncoated paper, increasing dot grain and decreasing resolution.
HP's Color-Lok technology is unrelated - it improves the performance of uncoated papers, not coated ones. Effectively, it's a different form of external sizing for the paper, giving the sizing some of the properties of an inkjet-receptive layer to prevent pigment migration along the fibres.
Shadowblade, you know I respect your opinions and your background, etc. May I point out that the evidence had from prior electron microscopic sampling of side views of cut paper has been rendered obsolete, since it has been recognized that side view sections cut with the best of blades alter the samples through squashing of the materials, no matter how careful. New techniques render historical and traditional views inadequate. A company called Sappi, cuts paper with an argon beam instead of a blade to aide in more accurate investigations.
As I say, without the equipment, expertise and background to back it up, I have a hunch that the ink does combine and lock into the fibers, and I will stick to my opinion, while at the same time thinking about what you are saying. I am not talking about an exaggerated sloppy combinations, just a level of "key" which enables a combinatorial intermingling of paper fibers with all the elements making up the interaction of ink and coating. I don't think the paper fiber can be left out of the equation, or why bother having matte papers at all? The interaction of the ink with the paper and the coating is significant in a combinatorial sense.
As for loading ink, I only am discussing what is found specifically in HP's bulletin regarding Quad inks:
"Fine Art Paper More Ink, which employs Quad Inks, (PK,MK,G, and LT G) and indicates the total amount of ink employed to maximize gamut without causing image quality problems. In general, the higher the ink limit, the higher the gamut. In general, the ink limit setting for Quad inks is 60 and is applied unidirectionally only."
I appreciate your position and respect your views. I accept a lot of what you say, however I also have my own understanding and experience having printed so much for so long.
Mark
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May I point out that the evidence had from prior electron microscopic sampling of side views of cut paper has been rendered obsolete, since it has been recognized that side view sections cut with the best of blades alter the samples through squashing of the materials, no matter how careful. New techniques render historical and traditional views inadequate. A company called Sappi, cuts paper with an argon beam instead of a blade to aide in more accurate investigations.
Mark
While I agree that microtomy and tradtional cross-sectional analysis has been superceded in some instances by newer tehniques, it is still practical and far from inadequate for many coated paper and media investigations. Certainly competent enough of a method to answer the questions being discussed in this thread :)
cheers,
Mark
http://www.aardenburg-imaging.com
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Shadowblade, you know I respect your opinions and your background, etc. May I point out that the evidence had from prior electron microscopic sampling of side views of cut paper has been rendered obsolete, since it has been recognized that side view sections cut with the best of blades alter the samples through squashing of the materials, no matter how careful. New techniques render historical and traditional views inadequate. A company called Sappi, cuts paper with an argon beam instead of a blade to aide in more accurate investigations.
I'm going on microscope views of cut paper, since I don't have access to a laser cutter.
Are there any images available of pigment penetrating into the base layer in a correctly-made (i.e. not overinked) print, cut using a laser cutter?
As I say, without the equipment, expertise and background to back it up, I have a hunch that the ink does combine and lock into the fibers, and I will stick to my opinion, while at the same time thinking about what you are saying. I am not talking about an exaggerated sloppy combinations, just a level of "key" which enables a combinatorial intermingling of paper fibers with all the elements making up the interaction of ink and coating. I don't think the paper fiber can be left out of the equation, or why bother having matte papers at all? The interaction of the ink with the paper and the coating is significant in a combinatorial sense.
What specific interactions do you think would happen, or could happen?
Clearly, interaction between pigment and substrate is not required, otherwise gloss papers, baryta papers, RC papers and films wouldn't work at all. In fact, a substrate isn't technically even required - you could print on a solid sheet of inkjet coating if you wanted to. Really, it's better to view an aqueous inkjet print as a microporous layer, holding an image, attached to a supporting and light-reflecting substrate. The microporous layer essentially acts like a filter for ink, separating out the solid pigment particles and allowing the liquid to pass through. No filter is perfect, though; when the filter is saturated, solid particles can also start to get through.
Certainly, there will be interaction between the carrier fluid and the substrate, provided it can reach the substrate. But, even if the pigment reaches the substrate, I can't see how there would be any chemical interactions between the pigment and the substrate at all. Remember, the resin encapsulating the pigment particles is designed to be as unreactive and chemically and physically stable as possible.
Why would you think there would be interaction between the pigment and the paper? Even if the pigment reaches the substrate, it's just going to sit on the surface of the fibres or sink deeper in to the paper base, moving through the gaps between the fibres. Pigment particles are a bit like dust or sand - they are solid particles, encapsulated in an unreactive resin. They just sit on whatever surface they adhere to, not reacting with them. Paper fibres are also stable, solid structures. Stable solid materials don't tend to do much when brought into contact with each other, except sometimes at extreme pressures and temperatures (at which point they're usually no longer solid nor stable).
Matte paper - like any other paper - is used for its appearance. Specifically, its texture. There are a lot of different papers out there, and a lot of different pigment ink formulations, and every single one of them is a usable combination. If pigment-on-substrate interaction occurred to any significant degree and affected the final image, there should be a lot of printer-paper combinations that just don't work.
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While I agree that microtomy and tradtional cross-sectional analysis has been superceded in some instances by newer tehniques, it is still practical and far from inadequate for many coated paper and media investigations. Certainly competent enough of a method to answer the questions being discussed in this thread :)
cheers,
Mark
http://www.aardenburg-imaging.com
OK Mark, fair enough. I'll accept that coming from you. :)
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The attached photo is a digital scan from a 35mm slide made with film camera attached to conventional microscope. This simple cross-sectional analysis is of a traditional RC chromogenic color print paper. From top to bottom one can make out:
1)very thin "supercoat" layer of gelatin (a bit hard to see but still observable in this photo, the clear supercoat gelatin layer is used to improve abrasion resistance of the dye-based image).
2) isolated cyan dye layer
3) isolated magenta dye layer
4)isolated yellow dye layer (all dye layers formed via color coupler chemistry during the silver halide processing step)
5) the dark and opaque layer imaged by the brightfield method is the TiO2 pigment white particles embedded in the top Polyethylene (PE) coating layer (the PE layers keep the water out of the paper core during processing).
5) The paper base sheet itself showing fibers and filler materials like calcium carbonate)
6) the clear PE bottom layer (i.e no TiO2 in this bottom PE layer) which lastly 7) has a thin gelatin layer (the dark band at the bottom) to give anti-curl layer assistance to the whole multl coated print structure. This bottom PE layer also has a rough calendared bottom surface which is why is looks so wavy. The calendaring gives this RC print a matte textured feel on the back side of the print, but it's all done with the roughened PE in this particular RC paper. Other RC papers actually embed some rough silica particles to perform the matting trick on the verso of the print.
Anyway, I made this photo over 20 years ago. With today's digital cameras, the image quality would be better yet, but even with the limitations of the cross-sectioning technique and film photography at the time, the observer can distinguish every layer sandwiched into this RC print paper technology. Inkjet papers have coatings of similar thicknesses, so this traditional microscopy technique should readily show whether colorants have reached the paper core or not. My experience is that dye based inkjet prints kept under humid conditions will allow the dyes to eventually diffuse beyond the primary ink receptor layer because unlike tradititional wet processed color prints, there is insufficient mordanting chemistry to keep those water soluble dye molecules anchored where they first dry down. In contrast, pigment prints will have those pigment particles trapped/adhered nicely very close to the top surface of the ink receptor layer, and they aren't going to go anywhere even though the water and glycol components will indeed diffuse further into the media. The glycol diffusion is going to go on for a very long time, and glycols are humectants, so in particular for RC inkjet papers, I suspect outgassing issues are not entirely resolved merely by letting inkjet prints "dry down" for a week or two before framing. The slow but inevitable off gassing will eventually require glazings to be removed, cleaned and reinstalled as time goes by.
I hope this photo helps frame (no pun intended) some of the points discussed in this thread :D
Edit: I should also mention that this photo shows a Dmax region of the RC color print, so all of the dye forming layers have generated maximum dye content during processing.
cheers,
Mark
http://www.aardenburg-imaging.com
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This is very interesting Mark. For 20 years ago, not bad. (To say the least).
Your findings are enlightening. You mentioned that inkjet coatings have coatings of similar thicknesses, etc., but I'm wondering if these coatings are, in today's time frame, speaking specifically about fine art Matte papers, similar.
I am particularly interested in your explanation of how and why dry down occurs and the implications regarding off-gassing.
Would this allow us to conclude that the phenomenon of the print "coming into focus" (a poor analogy) or actually becoming a cleaner, clearer print in a 24 to 48 hour period be due to evaporation?
In speaking just about Fine Art Matte papers, say Breathing Color Pura Smooth, and Epson Ultra Smooth Fine Art and any other equivalents, does the "wetness" meaning combinations of glycols, inks, etc., dry sufficiently via evaporation so that the print becomes altered at it's surface?
Can you shed light on this phenomenon?
I would be interested in a modern or updated microscopy test on fine art matte papers, during various phases and times of drying. Will pigment based inks diffuse similarly as your example from 20 years ago on an RC paper be the same as a current fine art matte paper?
I appreciate your taking the time to contribute this information, and would be interested in a similar test on Fine Art Matte papers.
Mark
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So for fun, I decided to see how a non-coated paper, properly profiled and calibrated using "Fine Art Papers More Ink" preset would fare without an inkjet coating and none of the barriers and glycols and humectants, etc, found in typical inkjet substrates.
I used Bienfang Drawing paper No. 527K Bristol Velum Surface for Pencil
There are two images below attached. The copies were made under really crappy florescent lighting.
I thought that there would be tremendous ink smearing, blotchy impossible to read colors, utterly devastating impossible ink blotting.
Hmmmmm. No such luck.
The first shows the calibration chart and the Atkins test image.
The second shows a 100% crop.
Granted, these images are nothing like what the Atkinson chart should actually look like on a coated paper.
But.....
Gotta say those blacks look pretty danged black - the black and white doesn't look bad. For no smearing.
Why and how could/would ink go down into the surface of matte papers, and what could it possibly do but mess up the print?
Mark
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So for fun, I decided to see how a non-coated paper, properly profiled and calibrated using "Fine Art Papers More Ink" preset would fare without an inkjet coating and none of the barriers and glycols and humectants, etc, found in typical inkjet substrates.
I used Bienfang Drawing paper No. 527K Bristol Velum Surface for Pencil
There are two images below attached. The copies were made under really crappy florescent lighting.
I thought that there would be tremendous ink smearing, blotchy impossible to read colors, utterly devastating impossible ink blotting.
Hmmmmm. No such luck.
The first shows the calibration chart and the Atkins test image.
The second shows a 100% crop.
Granted, these images are nothing like what the Atkinson chart should actually look like on a coated paper.
But.....
Gotta say those blacks look pretty danged black - the black and white doesn't look bad. For no smearing.
Why and how could/would ink go down into the surface of matte papers, and what could it possibly do but mess up the print?
Mark
After profiling the paper, what ink limits did you end up with? I'm guessing they were significantly lower than the ink limits on coated paper.
The difficulties with printing on uncoated paper are dot gain and non-uniformity of the surface. With regards to dot gain, this is because the carrier fluid - still containing the pigment - spreads along the randomly-distributed paper fibres, thus spreading more-or-less evenly in three dimensions - it spreads outwards as much as it spreads into the paper, causing dot gain. In contrast, on a coated paper, the ink is drawn down through the coating much more than it travels along the coating, and the vast majority of pigment is filtered by the topmost microporous layer. Think of an ink dot on uncoated paper as being more akin to a hemisphere spreading out from the intial do, and an ink dot on coated paper being more like a cylinder extending behind the initial dot, with most of the pigment being filtered out at the topmost layer of the cylinder. With regards to surface homogeneity, an inkjet coating is a more-or-less homogenous layer, which stays the same regardless of the paper texture underneath it. its surface irregularity is at a much finer scale than the surface irregularity of paper. With uncoated paper, the surface features exist at a much larger scale - whether an ink dot lands directly on a paper fibre, in a space in between fibres or on something else determines what the dot looks like and how it spreads. This is what causes the 'splotchiness' which can sometimes happen.
You can counteract the dot gain by reducing the ink load - less ink means that the pigment doesn't spread as far. Restrict it enough and the dots end up the same size as on coated paper, meaning minimal loss of sharpness (although the dots will still have feathery edges rather than the distinct, circular/square dots seen on coated paper). But this lower ink load also means less pigment, which means less colour. This could be compensated for by using a double-printing/re-registration process - the thing about uncoated paper is that, even though it can only handle a small amount of ink at the one time, you can't really over-ink it, since there's no surface coating which can be saturated. You can overprint it again and again. Naturally, this would only really be feasible with a flatbed aqueous printer, or some very good RIP software.
I've had a number of prints made using carbon inks on uncoated paper - they turned out very well, have Dmax to match many matte coated papers (although not the best ones) and far exceeding that of platinum prints, and should last even longer than platinum prints. Doubtlessly, a double-printing approach could improve the Dmax even more.
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After profiling the paper, what ink limits did you end up with? I'm guessing they were significantly lower than the ink limits on coated paper.
I kept the ink limit exactly the same as when using a coated paper specifically to prove the point that ink can bond to matte surfaces and create a stronger color base. The Quad Ink setting has an ink limit setting of 60. Many PK settings for coated papers are 30.
I just went to check the print, and indeed, as it is drying, the image is becoming clearer, cleaner, and sharper. In theory, what you say sounds good, yet in practice, the reality varries. The matte paper can carry the ink in an acceptable manner providing calibration and profiling are done carefully and with a correct setting. Either that ot the Z3200 is nothing short of miraculous.
The exact setting that would have been used on a coated fine art ink jet paper. Everything within certain parameters of acceptability meaning "in the ballpark".
If ink migrates through the microporous structure of coatings, I doubt very much it would harm the print in the specific case of Fine Art Matte Papers. I do believe it could strengthen the finished print providing a stronger base than merely residing solely on a layer suspended above the paper.
RC papers and coated shiny papers are not within the scope of my premise. I believe this applies only to Fine Art Matte Papers.
At any rate, I'll not argue further, as scientifically, I csan not prove this, and anecdotal examples admittedly fall short of definitive proof. So I have my theory which is somewhat demonstrated by the print on uncoated paper.
Either way, it is not really what the original topic was about, which was about dry-down time and the print improving over that waiting period.
It has been an interesting distraction, however.
Mark
Edits for spelling/typos
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I kept the ink limit exactly the same as when using a coated paper specifically to prove the point that ink can bond to matte surfaces and create a stronger color base. The Quad Ink setting has an ink limit setting of 60. Many PK settings for coated papers are 30.
I just went to check the print, and indeed, as it is drying, the image is becoming clearer, cleaner, and sharper. In theory, what you say sounds good, yet in practice, the reality varries. The matte paper can carry the ink in an acceptable manner providing calibration and profiling are done carefully and with a correct setting.
Exactly - it's all about the profiling. Profiling takes into account dot gain and everything else. The fact that the maximum allowable ink limit is 60 doesn't meant that that's how much is actually put down (although it wouldn't be unreasonable for blacks) - I would think that, due to the effects of dot gain, the actual amount of ink put down to produce any given colour (that lies within gamut) would be less than for a coated paper. But you'd have to look at the linearisation curves being generated to see this, not just the ink limit.
The image becoming clearer and sharper makes perfect sense - as it dries, light goes from reflecting off a grey, saturated paper base to reflecting off a white base. Nothing to do with whether
Either that ot the Z3200 is nothing short of miraculous.
The exact setting that would have been used on a coated fine art ink jet paper. Everything within certain parameters of acceptability meaning "in the ballpark".
It's not the same setting, though. You creased a profile for the paper. That's one of the major strengths of the Z3200 - it's very straightforward to create a new profile and print on just about anything.
If ink migrates through the microporous structure of coatings, I doubt very much it would harm the print in the specific case of Fine Art Matte Papers. I do believe it could strengthen the finished print providing a stronger base than merely residing solely on a layer suspended above the paper.
What do you mean by 'harm the print'? Also, what do you mean by 'ink'? Do you mean the pigment, specifically? Pigment particles are a bit like dust - it doesn't really form a solid bond with anything. It just gets stuck in the microporous coating, or on the external sizing of the paper fibres, but there's not much actually holding it to those surfaces other than friction and adsorption - it's certainly not any sort of adhesion. Particles that did adhere would be difficult to make ink from, because all the particles would stick together and rapidly give you a congealed mass at the bottom of the ink tank, unable to pass through the tubing, let alone through the print head. So, for that (and many other) reasons, they use nonreactive, non-adherent resin encapsulation - which, just like dust, can be easily brushed off a smooth printed surface. Just see what happens when you print on uncoated plastic or metal - there's no adhesion at all. Matte printed surfaces are more protected than completely smooth surfaces, because the particles are stuck in the microporous layer and can't be brushed off so easily, and gloss is even more protected, since the particles are stuck behind the gloss membrane in front of the print. But what's holding them there isn't any sort of adhesive force, but mere friction and mechanical obstruction, like fish caught in a net.
You can demonstrate this easily. Pour some ink into a container, and allow it to air-dry completely. You're left with a fine, dust-like powder. That's the encapsulated pigment - all the water, glycols, etc. have all evaporated. Rub it on a piece of uncoated paper. You'll find it has no adhesive properties whatsoever.
At any rate, I'll not argue further, as scientifically, I csan not prove this, and anecdotal examples admittedly fall short of definitive proof. So I have my theory which is somewhat demonstrated by the print on uncoated paper.
Either way, it is not really what the original topic was about, which was about dry-down time and the print improving over that waiting period.
It has been an interesting distraction, however.
Mark
I'm still not quite sure what the uncoated paper experiment was meant to demonstrate. That it's possible to print on uncoated paper?
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As I said, Doc:
"...At any rate, I'll not argue further, as scientifically, I can not prove this, and anecdotal examples admittedly fall short of definitive proof. So I have my theory which is somewhat demonstrated by the print on uncoated paper..."
Give it a rest my friend.
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I hesitate to get into the middle of one of these discussions, but FWIW, here are a few of my observations and what I've heard regarding a couple of the issues.
Printing on watercolor paper -- Arches Hot Press in particular -- can result in very good images, at least for black and white. My QTR profiles go easy on the ink limits for the dilute inks, but heavy at the black end. The Arches dmax is not reached until about 125% of the maximum QTR ink load. So, I have 2 MK ink positions in my printers.
The Arches smoothness will not be as good as a coated paper, but at "full sheet" (22x30 inches in the US) size, the normal viewer will not see the difference, and the critical viewer's appreciation of the underlying medium may offset the unevenness of some of the plain dark gray areas (like my heavily filtered skies).
If the loose fibers on the top surface of Arches are likely to cause too many "shadows" (white spots) in these dark, plain areas, I suggest printing on the backside of the paper. It has a texture I actually prefer in some respects. It seems to have fewer fibers sticking up off the surface.
BTW, remember to iron the deckle edges to avoid head strikes, and have fun figuring out how to deal with that deckle edge throwing off the printer's electric eye and image centering algorithms.
The advantages of a matte paper (any cotton based paper, probably) include that glycols have an "affinity" for cellulose and will likely just wrap themselves around those fibers and stay there, not outgas. (This is according to a PhD chemist.) The cellulose base, and particularly a cotton base, ends up taking care of much of the ink base products. The barrier papers have a problem in this respect.
I have and am backing away from the very dilute gray inks used in many dedicated B&W inksets because, in part, I don't think we know what all those base chemicals are going to do in the long run. Even in the short run, I see problems with putting too much water on the print. Our medium has proved itself worthy at this point. I no longer worry about people putting a loupe up to one of my prints and discovering that it is composed to tiny dots. I rather agree with the OEM companies that the LLK density is about as light as we usually need. After that, I wonder if the excess base chemicals are going to do more harm than good.
Paul
www.PaulRoark.com
http://www.paulroark.com/BW-Info/
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..........
Either way, it is not really what the original topic was about, which was about dry-down time and the print improving over that waiting period.
It has been an interesting distraction, however.
Mark
Edits for spelling/typos
Yes, I agree - it is an interesting discussion and reminds one that ink, paper and profiles are very critical variables in determining gamut and print quality, however defined. On the specific issue you raised about dry down time and print improvement over that period, not being an ink and paper chemist I cannot make any definitive statements about what really happens "under the hood", so this observation is empirical - i.e. based on what I see, and it is specific largely to several different PK papers printed in Epson 4900 or P800 printers using OEM inks and printer drivers mainly with custom icc profiles made in XRite software, so nothing exotic here. I find that I see some improvement in print clarity and shadow detail the morning after the night before, during which the prints are out-gassing in open air. The next morning I put them in archival storage boxes, the prints simply stacked. I went back to one of these boxes of prints I created some years ago, examined especially the backs of the prints, and saw no evidence of anything suggesting that chemical reactions having noticeable impacts were still occurring. So perhaps the real question is how much dry-down time is practically important; this experience for these materials would suggest about 12~24 hours.
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Exactly - it's all about the profiling. Profiling takes into account dot gain and everything else. The fact that the maximum allowable ink limit is 60 doesn't meant that that's how much is actually put down (although it wouldn't be unreasonable for blacks) - I would think that, due to the effects of dot gain, the actual amount of ink put down to produce any given colour (that lies within gamut) would be less than for a coated paper. But you'd have to look at the linearisation curves being generated to see this, not just the ink limit.
The image becoming clearer and sharper makes perfect sense - as it dries, light goes from reflecting off a grey, saturated paper base to reflecting off a white base. Nothing to do with whether
It's not the same setting, though. You creased a profile for the paper. That's one of the major strengths of the Z3200 - it's very straightforward to create a new profile and print on just about anything.
What do you mean by 'harm the print'? Also, what do you mean by 'ink'? Do you mean the pigment, specifically? Pigment particles are a bit like dust - it doesn't really form a solid bond with anything. It just gets stuck in the microporous coating, or on the external sizing of the paper fibres, but there's not much actually holding it to those surfaces other than friction and adsorption - it's certainly not any sort of adhesion. Particles that did adhere would be difficult to make ink from, because all the particles would stick together and rapidly give you a congealed mass at the bottom of the ink tank, unable to pass through the tubing, let alone through the print head. So, for that (and many other) reasons, they use nonreactive, non-adherent resin encapsulation - which, just like dust, can be easily brushed off a smooth printed surface. Just see what happens when you print on uncoated plastic or metal - there's no adhesion at all. Matte printed surfaces are more protected than completely smooth surfaces, because the particles are stuck in the microporous layer and can't be brushed off so easily, and gloss is even more protected, since the particles are stuck behind the gloss membrane in front of the print. But what's holding them there isn't any sort of adhesive force, but mere friction and mechanical obstruction, like fish caught in a net.
You can demonstrate this easily. Pour some ink into a container, and allow it to air-dry completely. You're left with a fine, dust-like powder. That's the encapsulated pigment - all the water, glycols, etc. have all evaporated. Rub it on a piece of uncoated paper. You'll find it has no adhesive properties whatsoever.
I'm still not quite sure what the uncoated paper experiment was meant to demonstrate. That it's possible to print on uncoated paper?
In custom RGB-device printer profiling, like most OEM drivers require, there is no access to the ink limitations, black generation etc. And the HP calibration only linearises what it sees as non linear in the calibration target, Dmax and maximum chroma will not be changed and by that the inklimits neither. The ink settings are in the media preset used, they do not change on profiling and only change within the ink limit range on calibration. The measurements + RGB-device printer profile creation just records the gamut available in the target print. If the aim is to control ink limitations etc too then at least some ink reduction in the HP media preset is possible or another choice from the media presets can cover that. HP gives some ink limit numbers for different media presets and the ink channels used, totals so little is known about black generation etc. RGB-device printer profile creation does not take dotgain etc into account, it just measures the individual target patches and creates the available gamut. Your assumptions on dotgain etc might apply on CMYKetc profiling with access to ink limits, black generation etc.
As I understand it Mark looked for some proof in what the differences are between uncoated and coated stock in print quality and his aim to lay down the same ink limited amount of ink is correct. His choice of a Bristiol drawing paper is not the best though as that kind of paper has a strong sizing and often is calandered to create a smoother surface. The fact that the print "developed" is already an indication of that, ink medium fluids did not really separate from the pigment and the pigment could not really sink in the fibers. The softest, most open fiber, conventional art papers are the etching papers. Papers used for stone printing already have more sizing. The proofs I made on conventional Arches Velin show less gamut and more dotgain. Actually the Olmec OLM15 a 25% cotton inkjet paper already shows a lower gamut, Dmax, more ink spread, uneven color areas, due to a cheaper coating. So do Red River's matte inkjet papers. You can get very good inkjet papers, with excellent coatings, on different paper bases but a plain good paper base, excellent fiber quality is no guarantee for an excellent inkjet print.
A print on the back of a quality inkjet paper usually delivers a way worse print than using the side meant for printing. Dual sided and semi-dual sided inkjet papers not counted. Hundreds of printer users will agree on that, often to their shame. They will have done the test as objective as possible, with exactly the same settings as used for the print side and their observations not influenced by anything else than the expectation of a nice print. Test results often presented as naive as possible to a forum like this one.
BTW, which pigment ink have you let dry down to a powder in a container? It does not resemble my practical experiences with several ink types over time, nor does it fit well with pigment ink components described in documents. PoliVinylAlcohol already creates a bond and the pigment encapsulation is closer to a gel than a hard plastic and will certainly create a bond with PVA in the coating or the sizing. The encapsulation is also there to keep that particle suspended, sounds contrary to the other effect but the conditions in the ink medium differ from the conditions on the paper. A good explanation of methods to prevent flocculation can be found here:
http://www.inkline.gr/inkjet/newtech/tech/dispersion/ General, not specific for inkjet ink pigments but other articles will specify the encapsulation technology for inkjet ink pigment particles.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2016 update, 700+ inkjet media white spectral plots
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In response to Ernst's discussion, I have created targets on three different substrates that have no calendaring, no size, no chemical additives or processes to make the papers receptive to inkjet ink.
Since the Z3200ps creates patches that are based on the preset used, I made targets only without going into creating ICC profiles for the papers. I doubt the ESP would make profiles anyway, since the papers all had very low white points.
The purpose of the test was to be able to observe the ink absorption of the paper and to test mainly for bleeding - one area or color into another. As the test plainly shows, bleeding occurs only at a microscopic level, presumably, since little is visible to the naked eye.
Quality of print was expected to be very low, however, many of the colors, and most of the grays and blacks faired well. The blacks well enough to actually print on with acceptable results, particularly with graphics.
I found an interesting quote from a thread back in 2013.
"Looks like various researchers have beaten me to it:
http://www.dp3project.org/preservation
Lots of useful articles there.
Bottom line: microporous layers crack very easily due to chemical as well as UV attack, and there's no easy way to restore them once they're cracked. The pigment inks which are printed on them are much more stable than the receptive layers themselves. According to micrographs, the paper base behind the microporous layer remains intact and undamaged. And sealing the back of a photo frame may not be the best idea after all.
I guess uncoated papers are the current solution for longevity after all. Now we just need to work out how to get inkjets to print on them better:
http://www.tappi.org/Downloads/Conference-Papers/2009/09PAPERCON/09pap33.aspx
Shadowblade - July 19, 2013, 11:49 AM..."
I don't mean to quote anything out of context, and please correct me if I have done so. This statement, no doubt applies to off-gassing, yet does indicate some interesting points.
Throughout our discussions it has been stated that ink and carriers stay on the top levels above a barrier and do not go beneath into the paper itself. It has also been stated that if the ink did go into the paper fibers, it would undoubtedly bleed and cause smearing or print degradation based on the inability of the paper (paper fibers) to hold the ink.
My test, albeit primitive and naive does indicate that uncoated papers can hold ink quite well and that the ink in fact does sink into the fibers of the paper and in so doing, does not bleed or smear.
I conclude that the receptors and coatings on Fine Art Matte are not all that there is to Matte papers.
Matte papers can stand almost on their own. Why is it such a stretch to imagine ink in fine art matte papers going down into the paper fiber base?
Anyway, Thanks everyone for humoring and indulging me. However I did not expect quite such a guantlet.
Thanks to those of you who have been kind in refuting my idea. Thanks to those of you who have attempted to understand what I'm getting at.
I've learned a lot from this discussion and I appreciate everyone's involvement.
Mark
The first image is of the three papers I made targets on using Fine Art Papers - Fine Art More Ink 60 IL
The following three images are 100% crops of the 3 papers with labels.
All photos were taken with an i-Phone handheld, and no processing. - just cropping.
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Yes, I agree - it is an interesting discussion and reminds one that ink, paper and profiles are very critical variables in determining gamut and print quality, however defined. On the specific issue you raised about dry down time and print improvement over that period, not being an ink and paper chemist I cannot make any definitive statements about what really happens "under the hood", so this observation is empirical - i.e. based on what I see, and it is specific largely to several different PK papers printed in Epson 4900 or P800 printers using OEM inks and printer drivers mainly with custom icc profiles made in XRite software, so nothing exotic here. I find that I see some improvement in print clarity and shadow detail the morning after the night before, during which the prints are out-gassing in open air. The next morning I put them in archival storage boxes, the prints simply stacked. I went back to one of these boxes of prints I created some years ago, examined especially the backs of the prints, and saw no evidence of anything suggesting that chemical reactions having noticeable impacts were still occurring. So perhaps the real question is how much dry-down time is practically important; this experience for these materials would suggest about 12~24 hours.
Hi Again Mark.
Thanks for your reply, again.
Yes, I agree - 12-24 hours, then stability.
Best -
Mark
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I hesitate to get into the middle of one of these discussions, but FWIW, here are a few of my observations and what I've heard regarding a couple of the issues.
Printing on watercolor paper -- Arches Hot Press in particular -- can result in very good images, at least for black and white. My QTR profiles go easy on the ink limits for the dilute inks, but heavy at the black end. The Arches dmax is not reached until about 125% of the maximum QTR ink load. So, I have 2 MK ink positions in my printers.
The Arches smoothness will not be as good as a coated paper, but at "full sheet" (22x30 inches in the US) size, the normal viewer will not see the difference, and the critical viewer's appreciation of the underlying medium may offset the unevenness of some of the plain dark gray areas (like my heavily filtered skies).
If the loose fibers on the top surface of Arches are likely to cause too many "shadows" (white spots) in these dark, plain areas, I suggest printing on the backside of the paper. It has a texture I actually prefer in some respects. It seems to have fewer fibers sticking up off the surface.
BTW, remember to iron the deckle edges to avoid head strikes, and have fun figuring out how to deal with that deckle edge throwing off the printer's electric eye and image centering algorithms.
The advantages of a matte paper (any cotton based paper, probably) include that glycols have an "affinity" for cellulose and will likely just wrap themselves around those fibers and stay there, not outgas. (This is according to a PhD chemist.) The cellulose base, and particularly a cotton base, ends up taking care of much of the ink base products. The barrier papers have a problem in this respect.
I have and am backing away from the very dilute gray inks used in many dedicated B&W inksets because, in part, I don't think we know what all those base chemicals are going to do in the long run. Even in the short run, I see problems with putting too much water on the print. Our medium has proved itself worthy at this point. I no longer worry about people putting a loupe up to one of my prints and discovering that it is composed to tiny dots. I rather agree with the OEM companies that the LLK density is about as light as we usually need. After that, I wonder if the excess base chemicals are going to do more harm than good.
Paul
www.PaulRoark.com
http://www.paulroark.com/BW-Info/
Thank you Paul - good to know. I like Arches...
Mark
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Unlike what happens in the wet darkroom, my understanding is that inkjet prints actually "dry up" very slightly rather than "dry down." In other words, the print will be very slightly darker when it first comes off the printer compared to later after it has dried. I've never actually measured this, but I think I've seen it visually, especially in the darker areas of the print. I'm sure this probably varies (maybe a lot) depending on the ink and paper being used.
Dave
Thanks for participating in this discussion Dave -
Pretty much my observations as well.
Mark
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Regarding my post about a "barrier layer", it's being taken too literally as a total moisture barrier. When ink jet papers are being coated, you need a base layer, commonly known as a "barrier" layer put down first to prepare the paper surface for subsequent coatings. Most inkjet papers have a number of coatings applied. There are several different ink jet receptor coatings also. Most common, today is the microporous receptor layer. In the early days of inkjet, attempts were made to print on all kinds of art papers. The most successful ones were "tub sized" papers using gelatin, most notably, Arches. (remember all traditional photo papers were coated with gelatin?) From this, modern ink jet paper coatings evolved. In any event, it is not desirable for the ink to penetrate into the base paper at all. As has been noted, the spectral qualities of ink jet ink come from the very top of the microporous layer. As ink drys, of course the image is subject to changes, just as a "wet pet rock" looks much different when it is viewed dry. (pardon the pet rock analogy)
The coatings are designed to prevent the "spread" of the ink droplet, preserving the small droplet size, and purity of the color.
Modern OEM pigmented ink has incorporated dispersants which function to keep the pigments from clumping and settling. They also have a "coating" agent like a polymer, that keeps the pigments strands separated, and also tends to create a contrasty look to the pigments (wet rock look), that enhances the d-max.
The water portion of the ink evaporates rather quickly, as has been noted. What takes longest, are the glycols, which can form a negative image film on a close-by glass surface. Most of the "dry down" is within 24 hours depending on ambient conditions. The glycols of course take much longer.
John Nollendorfs
Hi John -
Thanks for participating - appreciate your info and impressions.
Mark
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A further test. I folded and soaked paper towel and rubbed each printed example aggressively to see if the ink did penetrate deeply into the fibers.
I was surprised at the results. The paper which I expected to do the worst, (the paper mill blotter type paper) was unfazed. It kept drinking and soaking up the water like a sponge and the inks were largely unfazed as well.
Notice the wet paper towel in the paper mill blotter type paper. Very little ink came off after a lot of scrubbing. The more water I put on the tougher it became.
In each case, however, the test demonstrates that the ink did penetrate into the fibers and is relatively strong. Strong enough to withstand serious scrubbing.
Any surface coating would have long since been scrubbed away.
Mark