Results of six-month 'window test' on inkjet coatings

[Farmer]

Your own logic is defying you :-)

If the white paper reflects a lot of energy, then it can't be as hot on the "dark" side of the paper (not facing the sun) as on the "light" side of the paper (facing the sun and reflecting energy), furthermore, you have a very small layer of air between the paper and the glass which will be heated up and stay hot and without any direct convection won't move a lot.  On the "dark" side you have an entire room and thus don't get a layer of air trapped.  Furthermore, the glass itself, whilst transparent, will become at least warm and again act as a thermal mass, tending to keep that side hotter.

Sure, if you hold a paper cup for a while (thinner than most media, but I guess comparable) it gets too hot to hold over time.  Dip your finger into the liquid and it will burn you right away.

It's true that at some part of the day, a print on the wall may receive almost as much energy as a print on the window (less that lost due to passing through the glass and the related heat into the air etc) but as you noted, the exposure time for direct sunlight will typically be far less and it has the advantage of the thermal mass of the mounting and the frame and, to a lesser degree, the air behind it and the wall.  The temperature of the print is likely to be more consistent throughout the day and througout the substrate itself (i.e. less differential most of the time from one side to the other).  This is important when considering expansion and contraction of different materials at different rates.  More consistency, less extremes = less effect.  If that wasn't true, by your logic, prints on the wall would exhibit exactly the same problem as your ones on the window after a proportionately longer time (taking into account the lower direct sunlight hours), but clearly they don't.  Most of us here can point to prints which have hung for a decade or more without such issues.

[shadowblade]

Your own logic is defying you :-)

If the white paper reflects a lot of energy, then it can't be as hot on the "dark" side of the paper (not facing the sun) as on the "light" side of the paper (facing the sun and reflecting energy)

Given the thinness of the paper, this difference can be measured in fractions of a degree.

Furthermore, light that's *reflected*, by definition, doesn't heat the paper. Only light that's *absorbed* (e.g. by a dark surface) will heat the paper.

, furthermore, you have a very small layer of air between the paper and the glass which will be heated up and stay hot and without any direct convection won't move a lot.

There is *always* convection. The 1cm layer of air between the glass and the paper is connected to the air in the rest of the room. If it heats up, then, by definition, it will rise out of the way, allowing cooler air from beneath to take its place.

On the "dark" side you have an entire room and thus don't get a layer of air trapped.

Again, the thinness of the paper ensures that the temperature on one side is much the same as the temperature on the other.

Furthermore, the glass itself, whilst transparent, will become at least warm and again act as a thermal mass, tending to keep that side hotter.

Not when the paper isn't in direct contact with the glass.

Sure, if you hold a paper cup for a while (thinner than most media, but I guess comparable) it gets too hot to hold over time.  Dip your finger into the liquid and it will burn you right away.

That's not because of the temperature of the paper - that's because of the temperature, thermal mass, density and conductivity of the water.

Liquid water stores around 4.2kJ/kg for each degree that it's heated. It's also fairly conductive and distributes heat throughout its own mass via convection. At 1g/cm2, it's also much denser than paper. If you dip your finger into hot water, your finger rapidly reaches the same temperature as the water.

Paper, on the other hand, stores much less energy and does not undergo convection. If you touch a piece of hot paper, your hand will cool down the paper much more than it will heat up your hand (since your hand, essentially, is a bag of water).

For similar reasons, you could put your arm inside the 100 million degree plasma of some types of experimental fusion reactor and suffer no thermal effects (radiation is another matter entirely).

It's true that at some part of the day, a print on the wall may receive almost as much energy as a print on the window (less that lost due to passing through the glass and the related heat into the air etc) but as you noted, the exposure time for direct sunlight will typically be far less and it has the advantage of the thermal mass of the mounting and the frame and, to a lesser degree, the air behind it and the wall.  The temperature of the print is likely to be more consistent throughout the day and througout the substrate itself (i.e. less differential most of the time from one side to the other).  This is important when considering expansion and contraction of different materials at different rates.  More consistency, less extremes = less effect.  

The expansion and contraction of paper due to fluctuations in humidity is at least an order of magnitude greater than the expansion and contraction due to temperature.

If that wasn't true, by your logic, prints on the wall would exhibit exactly the same problem as your ones on the window after a proportionately longer time (taking into account the lower direct sunlight hours), but clearly they don't.  Most of us here can point to prints which have hung for a decade or more without such issues.

A decade, or even three or four decades, is insignificant for an inkjet print. I'm talking about the equivalent of 100-200 years of display.

Don't forget, high-quality microporous inkjet paper has only been around for a decade. The only long-lasting, photo-quality inkjet prints from before that were from Iris printers, which printed on uncoated paper.

[Farmer]

Ummm, no.  Reflected light comes back at a specific wavelength and in the process, some energy is transferred into the reflective medium.

Go ahead and test it - check the temperature on onside and the other, and note that the substrate is made of different materials on each side which will also affect it.

And 1cm between glass and paper?  You had that much bluetack on it?  And, no, if the gap is small enough it creates its own local environment, somewhat disconnected from the rest of the air - not entirely, but enough to produce a thermal difference.

[shadowblade]

Ummm, no.  Reflected light comes back at a specific wavelength and in the process, some energy is transferred into the reflective medium.

Reflected light comes back at whatever wavelength the incident light was at. If it comes back at a different wavelength, it wasn't reflected - rather, it was absorbed (usually causing an electron somewhere to jump into an 'excited' state) then re-emitted as a photon of a different wavelength.

Sunlight is made up of lots of different wavelengths. A coloured object will absorb some wavelengths more than others - the average wavelength of the reflected light defines its colour. A black object absorbs all visible light wavelengths more-or-less equally. A white object reflects all visible-light wavelengths more-or-less equally. This is why white objects appear white, and heat up minimally - almost all incoming light is reflected.

Go ahead and test it - check the temperature on onside and the other, and note that the substrate is made of different materials on each side which will also affect it.

And 1cm between glass and paper?  You had that much bluetack on it?  And, no, if the gap is small enough it creates its own local environment, somewhat disconnected from the rest of the air - not entirely, but enough to produce a thermal difference.

How else do you use blutack if not in big blobs?

It's a 32-degree day here in Melbourne today (that's outdoor shade temperature, the usual standard of measurement). Cooler indoors. I've had two pieces of paper blutacked to the window for the past two hours - a sheet of Hahnemuhle Photo Rag Pearl and a piece of black paper from a backdrop. I've also had a sheet of white paper, matted and framed (in a small, cheap, non-conservation frame with regular glass, i.e. what you'd expect of most people) sitting on a chair well away from the window, but still receiving direct sunlight, and a similarly-framed piece of black paper next to it.

Air temperature at the back of the room, never directly illuminated by the sun: 26.5 degrees
Air temperature behind the paper: 27.2 degrees
Air temperature between the paper and the window (~1cm gap): 27.7 degrees
Temperature of the white paper (side away from the window): 29.1 degrees
Temperature of the white paper (side facing the window): 29.5 degrees
Temperature of the black paper (side away from the window): 47.6 degrees
Temperature of the black paper (side facing the window): 47.8 degrees

Temperature of the white paper in the frame: 39.7 degrees
Air temperature in the frame with white paper: 39.7 degrees
Temperature of the black paper in the frame: 58.3 degrees
Air temperature in the frame with black paper: 54.2 degrees

A lot of 'obvious' things aren't so obvious when you actually measure them.

[Farmer]

So what we can discern is that there is a temperature differential and it's greater with white.  The paper, despite being white, is warmer than the ambient temperature, so it's not reflecting "everything".  The air trapped between the paper and the room is warmer than the room.  This is in line with what I and others have suggested.

Differences in temperature don't need to be an order of magnitude to have an impact on curling, for example.  The differences here of around 1-2%, particularly as there are different materials in the media, almost certainly have an affect, particularly when you expose them for 6 months over spring and summer.

There are a lot of variables and you're arbitarily attributing the results to some of them without isolating them.

Mark already made an excellent suggestion for a better test.

[hugowolf]

The temperature of the paper, as measured even on the hottest afternoon on the year, never exceeded 37-39 degrees and the circulation around paper Blu-Tacked to the window is much greater than any air circulation you'd have around a framed and matted print.

Besides, *any* print that is put in a location that receives direct sunlight will exceed 50 degrees at some point. ...

More than a little contradictory, no?

But still an interesting test.

Brian A

[shadowblade]

So what we can discern is that there is a temperature differential and it's greater with white.  The paper, despite being white, is warmer than the ambient temperature, so it's not reflecting "everything".  The air trapped between the paper and the room is warmer than the room.  This is in line with what I and others have suggested.

Differences in temperature don't need to be an order of magnitude to have an impact on curling, for example.  The differences here of around 1-2%, particularly as there are different materials in the media, almost certainly have an affect, particularly when you expose them for 6 months over spring and summer.

There are a lot of variables and you're arbitarily attributing the results to some of them without isolating them.

Mark already made an excellent suggestion for a better test.

Of course it's not reflecting everything. There's no such thing as a perfect reflector. But it's reflecting almost everything - if it weren't, it'd be a lot warmer than the ambient air temperature.

The temperature difference between the front and back of the paper is miniscule - less than 0.5 degrees. The 320gsm, coated white paper is a lot thicker than the thin, black backdrop paper, which is probably why the temperature difference between the front and the back is slightly greater for the white paper. Either way, the difference between the front and back is so small that you can safely use the temperature at the back of the paper as an analogue for the temperature at the front - it's not like there's a 5 or 10 degree difference between the two.

Regarding the air temperature, you're never going to have a perfectly-uniform temperature. But the difference between the temperature in front of the paper and the temperature behind the paper - or, indeed, the temperature at the back of the room - is only around a degree. If there were, indeed, significant air trapping there, creating a 'microclimate', the temperature there would be a lot higher - more like what you'd get in the truly enclosed spaces, such as in the frames.

Re: testing it with variable humidity/temperature without exposing to UV light - it's worth testing, but I doubt you'd see a result for decades, if not centuries. We already know that inkjet coatings are flexible when they're new and can cope with the base paper expanding and contracting with changing humidity. What we don't know is whether they can still cope with it after turning brittle (or not) with 100 years worth of UV exposure.

[shadowblade]

More than a little contradictory, no?

But still an interesting test.

Brian A

How is it contradictory? A piece of white paper won't get much hotter than the surrounding air temperature, since it reflects most incident light and derives its temperature largely through conduction from its surroundings.

In contrast, a printed paper gets much hotter than its surroundings when directly illuminated by sunlight, since it absorbs most of the incoming light. So a white piece of paper that reaches 39 degrees on a hot day in direct sunlight would easily reach >50 degrees if it were printed, particularly if it were printed in a dark colour.

Don't believe me? Find a white car and a black or dark blue car that have been sitting in the sun on a sunny day (easily found in any car park) and touch the bonnet of each car with the back of your hand. I can guarantee that the blue/black car will feel a lot hotter than the white car.

[shadowblade]

Re: testing printed, rather than unprinted paper

I suspect that printed paper would be more susceptible to cracking and peeling than non-printed paper, since porous papers are well-known for developing micro-cracks when drying after being heavily inked. These cracks can only weaken the coating.

[Farmer]

I wanted to add, because I've re-read some of my posts, that I think it's good that you've done this and the discussion is very interesting and potentially useful in leading to additional tests.  Apologies for coming off overly negative or harsh if I have.

I still think you're under estimating the effects of the differences that exist, btw :-)

[Paul Roark]

Interesting thread, and quite consistent with my expectations. 

I have a hierarchy in my prints from the RC (with B&W dyes) at the bottom (cheap, lots of pop, and sell well) and Arches un-coated watercolor paper with carbon pigments at the top (large size, very limited editions are of interest to collectors). 

I was curious about the observation that textured inkjet matte papers may not hold up as well as the smoother ones (if I understood the comment).  I talked once with an inkjet paper company rep about such things and got the impression from him that they had to back off from calendaring the paper too much.  I had the impression it was due to the paper needing some "tooth" for the coating to hang onto.  I had assumed this would suggest that the textured papers might actually have less problems with coatings separating, but maybe not.

Keep up the testing.  (Maybe include some Arches in the next sample?)

Paul
www.PaulRoark.com
http://www.paulroark.com/BW-Info/



 

[shadowblade]

Interesting thread, and quite consistent with my expectations. 

I have a hierarchy in my prints from the RC (with B&W dyes) at the bottom (cheap, lots of pop, and sell well) and Arches un-coated watercolor paper with carbon pigments at the top (large size, very limited editions are of interest to collectors). 

This is why I'm trying to get Arches Hot Press working with colour, using AIS Ultramax inks in an Epson printer. These have a higher-than-normal pigment load than OEM inks (apparently 70% ink load using Ultramax inks deposits as much pigment as 100% ink load using OEM inks) to compensate for the lower ink limit on Arches. The output will presumably be similar to output from an Iris printer, but with better gamut (due to using 10 different inks in 8 different colours, instead of just CMYK like Iris). A lot of my work looks much better in colour than monochrome, so I'd like to get this working.

On the other hand, I've potentially got a very good deal on a HP Z3200 within the next two days. I'm not sure how it will perform with uncoated paper, though, even with a RIP.

I was curious about the observation that textured inkjet matte papers may not hold up as well as the smoother ones (if I understood the comment).  I talked once with an inkjet paper company rep about such things and got the impression from him that they had to back off from calendaring the paper too much.  I had the impression it was due to the paper needing some "tooth" for the coating to hang onto.  I had assumed this would suggest that the textured papers might actually have less problems with coatings separating, but maybe not.

I didn't notice anything one way or the other re: the difference between rough papers and smooth papers. Maybe a longer test would eventually show that Canson Etching Edition or Breathing Colour Pura Velvet lasts longer than Rag Photographique or Pura Smooth. It makes sense that rough papers would hold on to coatings better than smooth papers, due to the increased surface area of the bond; however, textured papers have their own problems in that they're incredibly fragile and vulnerable to surface damage, even after spraying.

Keep up the testing.  (Maybe include some Arches in the next sample?)

Paul
www.PaulRoark.com
http://www.paulroark.com/BW-Info/

There's no point testing uncoated Arches when you're trying to test the long-term stability of a coating - there's literally nothing there to test!

[Ernst Dinkla]

On the other hand, I've potentially got a very good deal on a HP Z3200 within the next two days. I'm not sure how it will perform with uncoated paper, though, even with a RIP.

On good quality offset papers with little coating the Z3200 does a good job, not delivering the same gamut as possible on inkjet coated papers but better than what I experienced with other inkjet inks in the past. Paul has more experience with HP B&W inks on Arches art papers etc.


--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2014, 600+ inkjet media white spectral plots.

[shadowblade]

On good quality offset papers with little coating the Z3200 does a good job, not delivering the same gamut as possible on inkjet coated papers but better than what I experienced with other inkjet inks in the past. Paul has more experience with HP B&W inks on Arches art papers etc.


--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2014, 600+ inkjet media white spectral plots.

Thanks. How does the gamut compare to Iris prints?

Also, what do you mean by 'little' coating. Isn't it either coated or uncoated? I'm looking at watercolour papers, specifically Arches Hot Press. Or have you found a better option?

[Ernst Dinkla]

Quality offset papers have a light coating or similar improvements to achieve better print quality than possible on uncoated offset papers. There is a diffuse boundary between uncoated and coated papers if you count all the methods to get a smoother surface for printing: sizing methods, hot press satinizing, twin papers like Mellotex where the sieve sides of two thin papers interlock to create a thicker paper with no sieve sides, plate finished on both sides then. The paper I print on BioTop 3 belongs to uncoated in the catalogs but for me uncoated is more like what we call Roman here and what you will find in older cheap pocket books made in letterpress. Biotop paper qualities improved for web inkjet printing exist too, mainly dye inks are used in that industry and the paper made suitable for them and that fast printing process. Other big paper mills have similar qualities ready for that industry, hard to get for small shops; jumbo rolls. "infusion" you came across already, the surface polarity can be made suitable too for a specific printing process like inkjet.

The Arches qualities Paul uses are better compared to the uncoated Roman paper quality I referred to, though within the range of Arches papers the base sizing, surface sizing and surface treatment can be different for different print processes like intaglio, lithography, silkscreen, woodcut. The papers used for the Iris were taken from that range and had to cope with dye inks. The gamut of dye inks can be better on uncoated papers as there is little (inkjet head) penalty on increasing the colorant amount in dye inks. Color constancy, bleed, wet resistance, migration, light and gas fading are however way worse than what we have now in pigment inkjet inks. A fresh Iris print (no longer made) on Arches will probably be better in gamut than what I can make on that Biotop with my Z3200. The worst Iris prints considering longevity were actually made with Lyson Iris dye inks on Lyson rebranded Hahnemühle (German Etching for example) papers with an inkjet coating. Papers chosen because they delivered a better image resolution and gamut than the "uncoated" Arches papers.

Be prepared for a compromise in whatever you aim for.

--
Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2014, 600+ inkjet media white spectral plots.

[shadowblade]

Quality offset papers have a light coating or similar improvements to achieve better print quality than possible on uncoated offset papers. There is a diffuse boundary between uncoated and coated papers if you count all the methods to get a smoother surface for printing: sizing methods, hot press satinizing, twin papers like Mellotex where the sieve sides of two thin papers interlock to create a thicker paper with no sieve sides, plate finished on both sides then. The paper I print on BioTop 3 belongs to uncoated in the catalogs but for me uncoated is more like what we call Roman here and what you will find in older cheap pocket books made in letterpress. Biotop paper qualities improved for web inkjet printing exist too, mainly dye inks are used in that industry and the paper made suitable for them and that fast printing process. Other big paper mills have similar qualities ready for that industry, hard to get for small shops; jumbo rolls. "infusion" you came across already, the surface polarity can be made suitable too for a specific printing process like inkjet.

I took a look at Biotop 3 - it seems to be similar to what HP does with its ColorLok technology. I'd consider it uncoated, in the sense that there's no separate inkjet coating on top of the paper that can come unstuck with time. Unfortunately, all these papers seem to be fairly low-weight and low-grade compared to the 300-400gsm 100% cotton papers from Hahnemuhle and others, as well as the Japanese, Nepali and Indian handmade papers, that we commonly use in fine art and photography.

I really liked Hawk Mountain's Red Tail - I wish they still made it, or someone else made something like it. A heavy watercolour paper with Colorlok or similar technology (instead of an inkjet coating) would be nice, too.

The Arches qualities Paul uses are better compared to the uncoated Roman paper quality I referred to, though within the range of Arches papers the base sizing, surface sizing and surface treatment can be different for different print processes like intaglio, lithography, silkscreen, woodcut. The papers used for the Iris were taken from that range and had to cope with dye inks. The gamut of dye inks can be better on uncoated papers as there is little (inkjet head) penalty on increasing the colorant amount in dye inks. Color constancy, bleed, wet resistance, migration, light and gas fading are however way worse than what we have now in pigment inkjet inks. A fresh Iris print (no longer made) on Arches will probably be better in gamut than what I can make on that Biotop with my Z3200.

I was worried that would be the case, despite Iris only being a four-ink process.

I guess that's why I'm trying to have as wide a 'baseline' gamut as possible, in order to still be left with a wide gamut after imposing the ink limits for uncoated paper.

The worst Iris prints considering longevity were actually made with Lyson Iris dye inks on Lyson rebranded Hahnemühle (German Etching for example) papers with an inkjet coating. Papers chosen because they delivered a better image resolution and gamut than the "uncoated" Arches papers.

Not surprising, given that they're dye inks on porous paper.

I wonder if results would have been better using swellable paper rather than microporous.

Be prepared for a compromise in whatever you aim for.

I'm expecting to have to compromise gamut, but hope to be able to achieve somewhere near the gamut of coated matte papers. After all, you can get a Dmax of 1.60-1.65 on Arches (similar to many matte papers) and can push it up even further by heating the paper and increasing the ink load.

I had one of my prints made on Arches by Paul - it turned out very well. So, for black-and-white prints, I'm experimenting with a combination of MIS pure carbon pigments and Cone Piezography pigments, in order to produce a print that runs from neutral to slightly cool (depending on the lighting) in the shadows, to slightly warm in the highlights (a bit like split-toned selenium/sepia prints). But black-and-white prints on uncoated paper are a lot simpler, since you don't have to worry about ink lightfastness (carbon pigment being more-or-less permanent) or colour gamut, and you can easily do it on an old, second-hand seven- or eight-ink 9600 or 9800, whereas, for colour, you'd want a ten-ink 9900.

It'd be really nice to find a type of coated paper that remains supple, flexes with the paper and won't peel, crack or disintegrate over time. 'Infused' inkjet coatings certainly fit the bill (there being no layer to separate from the paper) - but I can't find anyone who makes one at the moment (although they sell infused, uncoated canvas). Stable coatings are certainly possible - after all, we have egg tempera paintings on wood dating from the early days of the Roman Empire. If one of these types of coated paper turns out to be stable, I wouldn't have to go through all this experimentation and accept a compromised gamut to produce highly-conservable premium-edition prints!

Do you have any photos of your Biotop/Z3200 prints that you can post, so I can see what sort of gamut you're getting?

[Paul Roark]

For best longevity, the only neutralized carbon (that is, carbon cooled with color pigments) I trust is HP's Z3200 PK, and grays.  The light grays are cooler than the PK diluted with the generic base.  Take a look at the graph on the top of page 11 of http://www.paulroark.com/BW-Info/7800-EbHP-2013.pdf to see how neutral a print made with 50% Eboni-6 (100% carbon) and 50% HP Z3200 PK, diluted with generic base can be.  With a Lab B rise of only one unit over the paper base, it looks dead neutral.  If the OEM dilutions of the HP grays had been used it would be even cooler.  But a one unit Lab B rise is virtually undetectable.

Paul
www.PaulRoark.com

[MHMG]

I really liked Hawk Mountain's Red Tail - I wish they still made it, or someone else made something like it.

Yup, I really saw something special in Red Tail, too, but I was involved in the R&D on that paper, so I have a personal bias.  Because a paper mill has to commit a full production run to doing an infusion trial (it's difficult to create the same properties on a smaller pilot line), the project was an expensive R&D effort. Developing a high quality infused paper is unlike developing new coating technologies where you can split off sections of the base paper run and do multiple coating trials to perfect the results. Lastly, printmakers like yourself, Paul and Ernst, indeed several of you who participate in the Lula Printers and Printing forum, represent about the 0.001 percentile of printmakers out there with your genuine interest and concern with longevity. You want to push the envelope and not take a "good is good enough" attitude towards the subject of print print quality and recognize that print permanence is also a fundamental property of a high quality print. I share those concerns, but from my perspective I don't feel we are main stream enough in our thinking or product expectations that we influence the "industry influencers" to any significant extent.

Anyway, Red Tail represented the last trial effort with the infusion project at that particular paper mill.  Hawk Mountain made a sweet deal to acquire that last lot and then convert it so that it could attempt to market it, Thus, this infused paper briefly entered the market as Red Tail, but not in time to help save Hawk Mountain which it probably wouldn't have anyway. There are too many suppliers out there right now (Ilford is the latest casualty). We will see more consolidation because the fine art printing and photographic printing market just isn't very big or growing as fast as it once was.  I guess we can thank smartphones, tablets, and Facebook for the rapid decline in photographic printing   That said, if I was a technical manager at one of the key media suppliers to the fine art digital printing market who will need to depend on retaining and gaining market share in this crowded market, I'd be looking at all these issues we've been discussing with a real R&D interest in finding more and more innovative ways to improve the product line.

From a technical perspective, Red Tail came close but still fell a little short on color gamut and dmax compared to the latest coated inkjet papers. However, most printmakers choose primarily on color gamut and image "pop", so the fact that Red Tail didn't excel in those factors was an understandable reason why the paper company management abandoned the effort even though that paper has other subtle and yes unique properties (e.g. fantastic lay-flat and double-sided printing properties ideal for book binding projects).

All that said, there was one last R&D trial I wanted to run,  and I genuinely believe that it would have gotten the color and density range at least to the point of meeting if not exceeding in color gamut and dmax, but by the time I"d gathered that technical insight, it was tool late to convince the paper mill's management to make one last effort.  Such is the reality of being a technical guy rather than a marketing guy.  Everyone of course, has to be on the same page, but marketing and accounting concerns always tend to trump R&D budgets unless the science and engineering appears to be headed in a rosy straight-line path. With truly innovative R&D a straight-line path to success is rarely the case.

best,
Mark
http://www.aardenburg-imaging.com

[shadowblade]

For best longevity, the only neutralized carbon (that is, carbon cooled with color pigments) I trust is HP's Z3200 PK, and grays.  The light grays are cooler than the PK diluted with the generic base.  Take a look at the graph on the top of page 11 of http://www.paulroark.com/BW-Info/7800-EbHP-2013.pdf to see how neutral a print made with 50% Eboni-6 (100% carbon) and 50% HP Z3200 PK, diluted with generic base can be.  With a Lab B rise of only one unit over the paper base, it looks dead neutral.  If the OEM dilutions of the HP grays had been used it would be even cooler.  But a one unit Lab B rise is virtually undetectable.

Paul
www.PaulRoark.com

I guess that's the beauty of printing on Arches Hot Press Natural - since the paper base is warm, 100% carbon MIS inks actually look cool against it! Not *really* cool, but cool enough to be used as the 'cool' end of a 'split-tone' carbon inkset (with Cone inks forming the lighter/less dense end of the spectrum).

[shadowblade]

Yup, I really saw something special in Red Tail, too, but I was involved in the R&D on that paper, so I have a personal bias.  Because a paper mill has to commit a full production run to doing an infusion trial (it's difficult to create the same properties on a smaller pilot line), the project was an expensive R&D effort. Developing a high quality infused paper is unlike developing new coating technologies where you can split off sections of the base paper run and do multiple coating trials to perfect the results. Lastly, printmakers like yourself, Paul and Ernst, indeed several of you who participate in the Lula Printers and Printing forum, represent about the 0.001 percentile of printmakers out there with your genuine interest and concern with longevity. You want to push the envelope and not take a "good is good enough" attitude towards the subject of print print quality and recognize that print permanence is also a fundamental property of a high quality print. I share those concerns, but from my perspective I don't feel we are main stream enough in our thinking or product expectations that we influence the "industry influencers" to any significant extent.

Anyway, Red Tail represented the last trial effort with the infusion project at that particular paper mill.  Hawk Mountain made a sweet deal to acquire that last lot and then convert it so that it could attempt to market it, Thus, this infused paper briefly entered the market as Red Tail, but not in time to help save Hawk Mountain which it probably wouldn't have anyway. There are too many suppliers out there right now (Ilford is the latest casualty). We will see more consolidation because the fine art printing and photographic printing market just isn't very big or growing as fast as it once was.  I guess we can thank smartphones, tablets, and Facebook for the rapid decline in photographic printing   That said, if I was a technical manager at one of the key media suppliers to the fine art digital printing market who will need to depend on retaining and gaining market share in this crowded market, I'd be looking at all these issues we've been discussing with a real R&D interest in finding more and more innovative ways to improve the product line.

From a technical perspective, Red Tail came close but still fell a little short on color gamut and dmax compared to the latest coated inkjet papers. However, most printmakers choose primarily on color gamut and image "pop", so the fact that Red Tail didn't excel in those factors was an understandable reason why the paper company management abandoned the effort even though that paper has other subtle and yes unique properties (e.g. fantastic lay-flat and double-sided printing properties ideal for book binding projects).

All that said, there was one last R&D trial I wanted to run,  and I genuinely believe that it would have gotten the color and density range at least to the point of meeting if not exceeding in color gamut and dmax, but by the time I"d gathered that technical insight, it was tool late to convince the paper mill's management to make one last effort.  Such is the reality of being a technical guy rather than a marketing guy.  Everyone of course, has to be on the same page, but marketing and accounting concerns always tend to trump R&D budgets unless the science and engineering appears to be headed in a rosy straight-line path. With truly innovative R&D a straight-line path to success is rarely the case.

best,
Mark
http://www.aardenburg-imaging.com

A huge pity, really.

I would have thought something like Red Tail, or another infused paper, would be something a small paper company could really use to carve a niche for themselves, offering something that no-one else can. Not something I would expect from Hahnemuhle or Canson, but something for a small, independent player to carve itself a place in the market that the big players don't cover. Even a fine-art-quality cotton rag paper treated with HP's Colorlok or similar technology would be nice. After all, it's not as if even 'standard' matte papers like Hahnemuhle Photo Rag have huge Dmax or colour gamut - yet people still use them despite the 'pop'.

And the really major application wouldn't even be in photography or art - it would be  in the preservation of important documents. Diplomas, signed contracts, treaties, historical documents, etc.

Kernow make several lines of infused, unprimed canvas (its Kernewek fabrics), but, as far as I know, no-one does the same for paper, apart from a few small sheets by Bockingford with poor test results.

Is the infusion process something that could be done by a small, independent paper maker (e.g. the kind that makes handmade artisan papers)? As in, does it use off-the-shelf inkjet coatings (similar to InkjetAid) applied in a different way, or is it a completely different substance? If it's something that can be done by any paper maker using off-the-shelf materials, it might be worth having such a paper maker produce a small batch as a trial run, and using it as a standard paper if it turns out well.