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Author Topic: Results of six-month 'window test' on inkjet coatings  (Read 36242 times)

Paul Roark

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #40 on: March 10, 2014, 03:38:39 pm »

[... 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! ...
[/quote]

That is part of it.  Also the un-coated papers usually print more neutrally than coated ones.  There is something about the coating that warms carbon.  A  minority of coated matte papers can come close.  I don't know enough about the process to know what the variables are, but I note the papers in my PDFs that are more "carbon friendly" in terms of having a low paper-base to peak-warmth differential.  Epson Hot Press Natural is one of them.

Visually, if the image is on the wall and isolated from brightened paper, the eye seems to do, in effect, a white balance on the paper base or mat board.  If that is the white point in the visual field, then how warm the image appears seems to be determined largely by the change in the Lab B from this paper base or matte board to the light and medium tones in the image.

Paul
www.PaulRoark.com
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MHMG

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #41 on: March 10, 2014, 04:14:50 pm »


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 Diplomas, signed contracts, treaties, historical documents, etc.


And what major players might that be? Museums and Archives are largely clueless about the new technologies. They tend to wait until modern stuff becomes an historic medium that they are then obligated to collect and understand.
Moreover, the overriding sentiment for experts in document and photo conservation is to rely on "proven" technologies that have existed for a long time, so a modern infused product would not pass that litmus test. I even see that sentiment expressed in this thread, with traditionally sized "uncoated" papers like Arches ColdPress getting the nod as far superior.

Few folks understand, for example, that "traditional" cotton papers aren't made the same way they were 100 years ago even though the marketing folks would have you believe the whole "we've been making this for 400 years" mystique. Does anyone really think 100% cotton means the product is 100% cotton?  It just means the linters going into the mixing vat might be 100% cotton. But paper contains many chemical additives. Traditional sizing agents like gelatin and starch, etc. have given way to more modern internal sizing agents like AKD, and modern optical brighteners are more of the norm than the exception. Just sayin... empirical knowledge of traditional media stability over time is extremely useful as is modern laboratory testing to determine modern durability issues. How many media vendors pay attention to all these long term durability issues if the product they make looks good on day one and is being praised by the consumer as the latest and greatest? That's where the enduser community has to demand more transparency on durability factors, and especially in this modern digital era (and throw-away society) I don't think we've done that as well as we could.

best,
Mark
« Last Edit: March 10, 2014, 04:30:59 pm by MHMG »
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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #42 on: March 10, 2014, 04:51:15 pm »

And what major players might that be? Museums and Archives are largely clueless about the new technologies. They tend to wait until modern stuff becomes an historic medium that they are then obligated to collect and understand.

Which is a very poor way of doing it. Much better to work out how to print something that will stand the test of time, than to not look into it and, forty years later, struggle to find a way to save important images and artworks which are fading or falling apart.

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Moreover, the overriding sentiment for experts in document and photo conservation is to rely on "proven" technologies that have existed for a long time, so a modern infused product would not pass that litmus test.

But the only 'proof' we have is that existing technologies for digital printing aren't very durable. Silver-gelatin fades rapidly compared to inkjet. Toner from laser printers and photocopiers falls off the paper. Inkjet is a very promising technology in terms of durability of the image and an increasingly important means of photographic output, displacing chromagenic prints - yet they haven't cared to test the durability of the material it's printed on!

Quote
I even see that sentiment expressed in this thread, with traditionally sized "uncoated" papers like Arches ColdPress getting the nod as far superior.

I wouldn't say it's superior - just that nothing else has been tested for anything other than lightfastness and anything with a coating layered on top of it (as opposed to impregnated within it) has an obvious weakness that could lead to its premature breakdown, well before the inks fade.

Quote
Few folks understand, for example, that "traditional" cotton papers aren't made the same way they were 100 years ago even though the marketing folks would have you believe the whole "we've been making this for 400 years" mystique. Does anyone really think 100% cotton means the product is 100% cotton?  It just means the linters going into the mixing vat might be 100% cotton. But paper contains many chemical additives. Traditional sizing agents like gelatin and starch, etc. have given way to more modern internal sizing agents like AKD, and modern optical brighteners are more of the norm than the exception. Just sayin... empirical knowledge of traditional media stability over time is extremely useful as is modern laboratory testing to determine modern durability issues. How many media vendors pay attention to all these long term durability issues if the product they make looks good on day one and is being praised by the consumer as the latest and greatest? That's where the enduser community has to demand more transparency on durability factors, and especially in this modern digital era (and throw-away society) I don't think we've done that as well as we could.

The rise in advertising and flashy, attention-grabbing, throwaway magazines over the past fifty or sixty years has a lot to answer for in that regard - printing has become more driven by short-term commercial applications than long-term storage of information. Books from 1800 hold up a lot better than books from 1950.

And the general public (most of whom are consumers of photos) haven't even thought about it at all. Case in point - have you seen a photo of your great-grandmother as a child? Quite possibly - if she had her photo taken, it was probably as a platinum print. What about your grandmother? Very likely, too - it was probably a silver-gelatin print, toned to completion with sepia, selenium or gold, with minimal fading (untoned prints would have exhibited significant fading). What about photos of your mother as a child? Probably not too many - most of these are likely to be colour chromogenic prints and would have faded significantly since then. And what about your own childhood photos? These are probably colour chromogenic prints made on RC paper and deteriorate significantly after just 20-30 years. Given how much your photos, and those of your mother, have deteriorated, how do you think they'll look in 50-100 years' time? Your grandchildren will probably still have photos of your grandmother and great-grandmother, but those of you and your mother would have long since faded or disintegrated. But most people haven't had it put to them like that.
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MHMG

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #43 on: March 10, 2014, 05:12:04 pm »


And the general public (most of whom are consumers of photos) haven't even thought about it at all. Case in point - have you seen a photo of your great-grandmother as a child? Quite possibly - if she had her photo taken, it was probably as a platinum print. What about your grandmother? Very likely, too - it was probably a silver-gelatin print, toned to completion with sepia, selenium or gold, with minimal fading (untoned prints would have exhibited significant fading). What about photos of your mother as a child? Probably not too many - most of these are likely to be colour chromogenic prints and would have faded significantly since then. And what about your own childhood photos? These are probably colour chromogenic prints made on RC paper and deteriorate significantly after just 20-30 years. Given how much your photos, and those of your mother, have deteriorated, how do you think they'll look in 50-100 years' time? Your grandchildren will probably still have photos of your grandmother and great-grandmother, but those of you and your mother would have long since faded or disintegrated. But most people haven't had it put to them like that.

Preaching to the Choir :) But the Chapel is small, and few folks are in attendance ;) Sorry to sound cynical. I wouldn't do what I'm doing if the apparent cynicism overwhelmed me. Van Gogh comes to mind. He didn't sell a single painting in his lifetime (except to his brother who wanted to support him) and unlike me he got frustrated enough to cut off his own ear, and questionable history has it recorded that he eventually took his own life. Nonetheless, he believed passionately in his own work and kept doing it when the financial aspects of the matter indicated clearly he should pursue something else. I do wish he'd spent a little more effort evaluating the color pigments he chose. A few important ones in his palette weren't very light fast ;)
« Last Edit: March 10, 2014, 05:22:38 pm by MHMG »
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Wayne Fox

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #44 on: March 10, 2014, 05:23:53 pm »

There's no 'close range' when it comes to sunlight. It all comes from the same source 150 million kilometres away. If an object is receiving direct sunlight, it makes no difference whether it's 1cm away from the glass or 10m behind it.

In a vacuum, yes. In an environmentally controlled room, no. And attached to the glass definitely not.  I don’t think any of these papers were designed for sustained exposures in the 40c range.  That much  heat is hard on anything, especially with no circulation.

As I said, interesting and I applaud the effort because I think we are all concerned with the long term stability and durability of inkjet papers and their receptor coats, but I don’t think there is a scientific test that can be applied short term to extrapolate long term affects. There just isn’t any way to accelerate an aging test for this type of deterioration by exaggerating the conditions.

One other thought, seems like the test you made would also most likely have faded the images beyond use, so whether the paper makes it or not might not matter because the image wouldn’t make it.
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MHMG

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #45 on: March 10, 2014, 05:54:11 pm »

... but I don’t think there is a scientific test that can be applied short term to extrapolate long term affects. There just isn’t any way to accelerate an aging test for this type of deterioration by exaggerating the conditions.

Actually there is. One needs to collect material properties like humidity and temperature coefficients of expansion for each of the component layers, plus the stress and strain-to-break limits, and the thicknesses of each layer which can all be done in a laboratory if one has access to the materials. Then input the data into a computer model using an analytical tool called finite element analysis well known to mechanical engineers, and one can predict the elastic-plastic deformation problems that will occur in the finished piece pretty darn well. This approach to the problem was the subject of research I participated in over twenty years ago with my colleagues Drs. Mecklenburg, Tumosa, and Erhardt at the Smithsonian Institution. It's a subject near and dear to my heart, but regrettably takes some equipment I don't have at Aardenburg Imaging & Archives, otherwise I'd be pursuing this issue on a much more rigorous level.

The work was quite controversial at the time because the results of our research eventually called into question the need for highly "flat-lined" environments (i.e. very precise and expensive control of temperature and humidity in the storage and display areas) which was the consensus thinking at the time in the Museum and Archives community. Our findings did not suggest one could be cavalier with regard to controlling the indoor climate as the critics claimed we were advocating , but one could indeed loosen the tolerances safely to wider than  ±2F and ± 2%RH that was being recommended by most conservators at the time, up to ± 15%RH on the humidity range and in some cases very wide on temperature. It was the safe and allowable temperature range I was particularly interested in for the Smithsonian's incredible photographic collections because one could not pursue cold storage of photographic collections without proof that this amazing conservation procedure was physically safe for the collection materials.
  
The current trends towards a "greener" more "sustainable" and hence affordable indoor climate control policy in the museum and archives community has brought about a revisitation of our research findings in these modern times, and oddly enough, our early research on this subject is much more favorably regarded (and vindicated as well) in today's museum and archives community :)

cheers,
Mark
http://www.aardenburg-imaging.com
« Last Edit: March 10, 2014, 06:16:50 pm by MHMG »
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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #46 on: March 10, 2014, 05:59:54 pm »

Quote from: Wayne Fox link=topic=87926.msg717414#msg717414date=1394486633
In a vacuum, yes. In an environmentally controlled room, no.

I suggest that you go and actually measure the light level in a sunlit room, firstly next to the window, then on the opposite side of the room (but still receiving direct sunlight through the window). You'll find that the incident light level is identical. Do some actual experimentation instead of criticising without results or a scientifically-defensible theory to back it up. 'It feels hotter' or 'it looks brighter' doesn't actually mean that it is.

Conjecture and 'what it feels like' are often not consistent with what you find when you actually mention things. It feels a lot hotter next to a window with sunlight streaming in, than on the opposite side of the room away from the sun. The air temperature, when you measure it, will be more-or-less identical. It only feels hotter because you're getting warmed by radiant heat from the sun. But the paper, being near-white, barely gets heated (printed paper is a different story altogether).

Quote
And attached to the glass definitely not. 

So, a sample receives stronger UV light just because it's attached to the glass rather than 3m behind the glass? Inverse square law says not - not when the source of light is 150 million kilometres away.

Quote
I don’t think any of these papers were designed for sustained exposures in the 40c range.  That much  heat is hard on anything, especially with no circulation.

In other words, you're saying that these papers aren't designed to be framed. A frame has less air circulation than anything else, and gets much hotter than unframed paper, even with short (1-2 hours) periods of direct sunlight.

Quote
One other thought, seems like the test you made would also most likely have faded the images beyond use, so whether the paper makes it or not might not matter because the image wouldn’t make it.

Light exposure during a six-month period would have been well under 100 Mlux hours, most likely around 50 Mlux hours. That wouldn't have been enough to significantly fade any of the inkjet prints. Images are useful for significantly longer than the times listed on Aardenburg - those exposure levels are for when fading first becomes visible, not for when the images become useless.
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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #47 on: March 10, 2014, 06:12:45 pm »

Actually there is. One needs to collect material properties like humidity and temperature coefficients of expansion for each of the component layers, plus the stress and strain-to-break limits, and the thicknesses of each layer which can all be done in a laboratory if one has access to the materials. Then input the data into a computer model using an analytical tool called finite element analysis well known to mechanical engineers, and one can predict the elastic-plastic deformation problems that will occur in the finished piece pretty darn well. This approach to the problem was the subject of research I participated in over twenty years ago with my colleagues Drs. Mecklenburg, Tumosa, and Erhardt at the Smithsonian Institution. It's a subject near and dear to my heart, but regrettably takes some equipment I don't have at Aardenburg Imaging & Archives, otherwise I'd be pursuing this issue on a much more rigorous level.

The work was quite controversial at the time because the results of our research eventually called into question the need for highly "flat-lined" environments (i.e. very precise and expensive control of temperature and humidity in the storage and display areas) which was the consensus thinking at the time in the Museum and Archives community. Our findings did not suggest one could be cavalier with regard to controlling the indoor climate as the critics claimed we were advocating , but one could indeed loosen the tolerances safely to wider than  ±2F and ± 2%RH that was being recommended by most conservators at the time, up to ± 15%RH on the humidity range and in some cases very wide on temperature. It was the safe and allowable temperature range I was particularly interested in for the Smithsonian's incredible photographic collections because one could not pursue cold storage of photographic collections without proof that this amazing conservation procedure was physically safe for the collection materials.
  
The current trends towards a "greener" more "sustainable" and hence affordable indoor climate control policy in the museum and archives community has brought about a revisitation of our research findings in these modern times, and oddly enough, our early research on this subject is much more favorably regarded (and vindicated as well) in today's museum and archives community :)

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

Of course, stress and elastic limits change with time, as coatings are exposed to UV light and atmospheric pollutants - something that a fresh piece of paper can withstand may be too much for a 50-year-old piece of paper. Hence the need for accelerated ageing tests, to age these coatings to the equivalent of hundreds of years of normal display.

I guess I'm not so concerned with the means and methods conservators use, but how to produce a print that will stand the test of time outside of a controlled or museum environment. Most of my prints don't go to carefully-stored archives. They go to homes everywhere from deserts to the humid tropics, to centuries-old temples with no climate control, to displayed collections in desert forts and damp, musty wineries. They're looked after by people who wouldn't know the slightest thing about paper and printing, not curators who have studied it their whole lives. I'd like to make prints that will stand up to real-world conditions, not just in carefully-controlled archives and libraries.
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MHMG

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #48 on: March 10, 2014, 06:16:08 pm »

Of course, stress and elastic limits change with time, as coatings are exposed to UV light and atmospheric pollutants - something that a fresh piece of paper can withstand may be too much for a 50-year-old piece of paper. Hence the need for accelerated ageing tests, to age these coatings to the equivalent of hundreds of years of normal display.


Correct, and can be done in the lab and input into the model. Been there, done that.

This is my last post on Lula for a while, friends. I want to go make some prints and do some photography!!!

cheers, mark

P.S. thank you Shadowblade et al, for a stimulating discussion.
« Last Edit: March 10, 2014, 06:18:06 pm by MHMG »
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Wayne Fox

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #49 on: March 10, 2014, 07:30:37 pm »

I suggest that you go and actually measure the light level in a sunlit room, firstly next to the window, then on the opposite side of the room (but still receiving direct sunlight through the window). You'll find that the incident light level is identical. Do some actual experimentation instead of criticising without results or a scientifically-defensible theory to back it up. 'It feels hotter' or 'it looks brighter' doesn't actually mean that it is.



but I'm not (and have never been) referring to the amount of light. Most of the degradation you describe was not caused by the light, but by the thermal conditions of the test.

I guess I could get a thermometer of some type and test the temperature of the two conditions pretty easily, but considering it's a piece of white paper I don't think it would even get warm across the room.  But then again, I'm having trouble with my motivation, because I can't see any relevant conclusions to your non scientific  test that are applicable to conditions normally experienced by images on a wall in a room.  I think Mark mentioned how extremely difficult it is to to accelerated testing on this stuff, and we all know that storing prints in a warm environment for extend lengths of time is bad on them, nothing new there.

Anyway, enough for me ...

good luck with whatever you are trying to figure out ...
« Last Edit: March 11, 2014, 01:29:38 pm by Wayne Fox »
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Farmer

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #50 on: March 10, 2014, 08:46:13 pm »

FWIW, you don't get the same amount of sunlight (direct or otherwise) on a print on the window as you do one back on the wall.  On the window, the maxium amount of light is available and striking it.  In the room, that light is filling the entire room, not just landing on that one surface, so the exposure must be less, even when "direct".  Some of it will reflect of other surfaces and may eventually make it to the print, but it will still be less.
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Phil Brown

shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #51 on: March 10, 2014, 11:01:39 pm »

FWIW, you don't get the same amount of sunlight (direct or otherwise) on a print on the window as you do one back on the wall.  On the window, the maxium amount of light is available and striking it.  In the room, that light is filling the entire room, not just landing on that one surface, so the exposure must be less, even when "direct".  Some of it will reflect of other surfaces and may eventually make it to the print, but it will still be less.


Once again, completely not true.

Light enters through the whole window, not just the part of the window covered by the print. The amount of light hitting the print depends entirely on the intensity of the incoming light, measured in lux. Since the point source of light is hundreds of millions of kilometres away, the difference in intensity of light from one end of the room to the other (a few metres) is negligible - the intensity of direct sunlight at the window will be the same as the the intensity of direct sunlight at the back of the room. Just that an object near the window will be subject to direct sunlight for a longer period of time each day than an object at the back of the room.

If you don't believe me, measure it yourself.
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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #52 on: March 10, 2014, 11:24:01 pm »

but I'm not (and have never been) referring to the amount of light. Most of the degradation you describe was not caused by the light, but by the thermal conditions of the test.

You keep harping on about the 'thermal conditions' the print is exposed to, but haven't even accounted for the fact that a framed print, due to being stored in what's essentially a tiny, enclosed space with zero air circulation, gets a *lot* hotter with even a brief exposure to direct sunlight than an unframed print sitting in the same direct sunlight all day. And a printed piece of paper gets a lot hotter than a unprinted piece of the same paper, since it absorbs a lot more solar radiation. A white object derives its temperature largely from the air temperature around it, since most radiant heat/light is reflected rather than absorbed. And there will be next to no difference in air temperature from one side of a room to the other.

Moreover, it's been established that dimensional changes in paper caused by changes in humidity are at least an order of magnitude greater than changes caused by temperature. Compared to what humidity does to paper, the effect of temperature is insignificant. When you're doing a qualitative, rather than quantitative test (e.g. working out which paper breaks down first, rather than exactly how much exposure is needed for an individual paper to break down) the effects of temperature are further neutralised, since every sample is being put through the same conditions.

And a basic knowledge of chemistry will tell you that, unless you're melting something or denaturing proteins, temperature doesn't *cause* breakdown. It merely accelerates it, like it accelerates any other chemical reaction.

Quote
I guess I could get a thermometer of some type and test the temperature of the two conditions pretty easily, but considering it's a piece of white paper I don't think it would even get warm across the room.  But then again, I'm having trouble with my motivation, because I can't see any relevant conclusions to your non scientific  test that are not applicable to conditions normally experienced by images on a wall in a room.  

Exactly - it won't get warm across the room, and it won't get warm next to the window either. Being a white object, it will stay near the ambient air temperature.

Why don't you get a printed image (any printed image will do), put it in a frame with a mat board and a thermometer and put it in direct sunlight in summer for even a few minutes, and see what the air temperature in the frame is? Then you'll see how a framed print gets much, much hotter than an unframed piece of white paper in a very short period of time, making temperatures of 40-45 degrees seem cool in comparison. After all, even an enclosed space as large as a car gets extremely hot in a few minutes. The frame is many times smaller and has a huge radiation collecting surface area (the print area) compared to the volume of air within it.

Quote
I think Mark mentioned how extremely difficult it is to to accelerated testing on this stuff, and we all know that storing prints in a warm environment for extend lengths of time is bad on them, nothing new there.

Anyway, enough for me ...

good luck with whatever you are trying to figure out ...

Of course storing prints in a warm environment is bad for them. That's why it's worth testing. Because, outside of archives and well-maintained collections, prints put on display are subject to everything from freezing winter temperatures, to hot, dry conditions, to fumes from cooking, to cigarette smoke, to 100% humidity. If you want prints that will last in a real-world environment, not just when carefully maintained in a collection by conservation experts, you need to print on material that can withstand all these conditions.

***

Essentially, what you're saying is that the results are irrelevant, since you believe that no print normally displayed (in a home, shop or wherever) would be subject to the temperatures experienced by the paper in the test.

To back up your argument and make it more than conjecture, what you'd need to do is take a framed, matted, printed piece of paper, expose it to direct sunlight for 15, 30 or 60 minutes on a hot day and measure the surface temperature of the print as well as the air temperature within the frame. If it doesn't get much hotter than ambient air temperature, then your argument has merit. But what you'll find is that the temperature in the frame and on the printed paper will get a *lot* hotter than ambient air temperature, and hotter than anything experienced by the papers in my test.

You need to stop passing off opinion as 'fact' and actually provide some evidence refuting the test results or conditions - measured temperatures or light levels showing huge differences in light or temperature from one end of the room to the other, or measurements of temperatures in frames - or an argument you can back up with established scientific theory (e.g. differences in illumination from one end of the room to the other, backed up by the inverse square law). Otherwise everything you're saying is pretty much conjecture, with no basis in fact other than you not liking the results.
« Last Edit: March 10, 2014, 11:57:58 pm by shadowblade »
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Farmer

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #53 on: March 11, 2014, 12:38:28 am »

All we've been saying, really, and continue to say, is that the input variables are numerous and you have not isolated them for your results.  You are presenting results and then drawing conclusions.  It's little different to speculation when you have no way of falsifying the results you're presenting.

You also dismissed the results that confirmed what I had been saying about temperature differentials - your results exactly confirmed the variations that I predicted.  You say the differences are too small to matter, but you haven't tested anything to verify that.

It's a good subject and a good test, but your results are not comprehensive - there's room for more testing, not least of which is to isolate the various factors that could be contributing to try to determine what it is that's actually causing the issue, rather than assuming the answer.
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Phil Brown

shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #54 on: March 11, 2014, 02:11:22 am »

All we've been saying, really, and continue to say, is that the input variables are numerous and you have not isolated them for your results.  You are presenting results and then drawing conclusions.  It's little different to speculation when you have no way of falsifying the results you're presenting.

You also dismissed the results that confirmed what I had been saying about temperature differentials - your results exactly confirmed the variations that I predicted.  You say the differences are too small to matter, but you haven't tested anything to verify that.

It's a good subject and a good test, but your results are not comprehensive - there's room for more testing, not least of which is to isolate the various factors that could be contributing to try to determine what it is that's actually causing the issue, rather than assuming the answer.

Quite the opposite, really.

Long-established knowledge gives us the following facts as a starting point:

1. That paper is a hygroscopic material, and that a sheet of paper changes its dimensions significantly as the relative humidity of the surrounding air changes.

2. That the coefficient of thermal expansion of paper, taken as a whole sheet, is extremely low - less than glass, metal, concrete, plastics of all kinds and even graphite. Part of this is due to the porous nature of paper - individual fibres may expand (although the coefficient of thermal expansion even of individual fibres is very low in the longitudinal direction, and still fairly low across the fibre) but, when they expand, they simply fill the gaps between the fibres, rather than causing the sheet of paper to expand as a whole.

3. That the major source of stress at an interface between two layers made of different materials is the difference in dimensional change between the two materials when exposed to the same environmental conditions. This is regardless of what the two materials are - paper and coating, copper and zinc, concrete and steel.

4. That the response of the individual layers to stress at the interface depends on the Young's modulus and yield points (elastic limit and fracture point) of the material, as well as the strength of the bond between the two materials.

5. That exposure to ultraviolet light and atmospheric pollutants can alter the physical characteristics of a material, particularly a material based on organic molecules.

From your arguments, you obviously disagree with point (2), but the results of my second experiment demonstrate that point 2 isn't even relevant when considering the results of the first experiment.

From these principles, we can infer the following hypotheses:

1. That the Young's modulus and yield points of a material (in this case, the inkjet coating) can change as the material is altered on exposure to ultraviolet light and atmospheric pollutants. Therefore, a stress that doesn't affect a new coating (e.g. reducing the RH to 10%) could possibly cause failure in a coating whose stress-strain characteristics have been altered by UV light and pollutants.

2. That failure of a coating material can occur either within the coating material itself (cracking, buckling and disintegration) due to the stress in the material exceeding the yield points of the material, or at the junction between the coating material and the substrate (delamination and 'flaking'), due to failure of the bond between the two materials.

3. That the vast majority of dimensional change in paper is due to hygroscopic effects rather than thermal expansion.

Obviously, you disagree with the third hypothesis. But the second test I performed renders that argument irrelevant (explanation further down).

The first test establishes the following:

1. That different papers fail at different rates, depending on their general structure - coating on polythene on paper, or coating on baryta on paper, or coating directly on paper.

2. That the mechanism of failure seems to differ between papers - delamination of the coating on RC papers, delamination and cracking of the baryta layer in the baryta papers, and no obvious failure seen in the coating-on-paper papers (although other studies have shown that microporous layers develop microscopic cracks under heavy ink loads).

You contended that the test is irrelevant, because putting prints up against a window exposes them to much greater peak temperatures as compared to a framed, matted print hanging on a wall away from the window and exposed to sunlight for 1-2 hours at a time. The second test refutes that.

The second test establishes the following:

1. That the temperature of an unframed piece of white paper remains near the ambient room temperature (1 or 2 degrees warmer) even when in direct sunlight.

2. That the front and back of a piece of paper remain within around half a degree of each other when one side is exposed to strong solar irradiation.

3. That the air temperature in the small gap between the paper and the window is similar (less than 2 degrees warmer) to the air temperature at the back of the room, out of direct sunlight.

You contend that these small temperature differences matter, however small they may be and, therefore, invalidates the results. However, the other part of the test completely invalidates your argument. The tests involving black paper and framed paper establish:

4. That dark paper (e.g. prints) becomes a lot hotter than white paper when exposed to the same level of solar irradiation, greatly exceeding the surrounding air temperature. Therefore, a typical print would become much hotter than my unprinted paper samples when exposed to the same level of sunlight.

5. That prints enclosed in a frame behind glass get a lot hotter than unframed prints or paper, even when the prints/frames are well back from the window. Therefore, a framed print gets a lot hotter than an unframed print when exposed to sunlight. That's not to say that there aren't other protective features of framing that make it worthwhile, but that protection from the thermal effects of direct sunlight isn't one of them.

The fourth and fifth findings of the second test render all the arguments about 'extreme temperatures' completely invalid, since they show that a piece of printed paper well back from the window (but still receiving an hour or so of direct sunlight) and enclosed within a frame gets much hotter than a white piece of paper up against the window - much more than the 1 or 2 degrees above room air temperature experienced by the unframed white paper.

Essentially, what the second set of tests show is that the 'extreme temperature' argument against the results of the first test are invalid, since they show that a framed print will be exposed to much higher temperatures than a white, unframed piece of paper ever will.
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Ernst Dinkla

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #55 on: March 11, 2014, 04:51:08 am »


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.

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?

The Iris dyes on uncoated Arches were more light resistant than on the inkjet coated Hahnemühle. It is not the paper porosity but the coating porosity etc that had an effect. At that time the pH grade of the inks and the pH of the media was considered to play a role on that aspect. Dyes + cotton could build on textile coloring technology and did so to a degree. Swellable paper was the other direction that delivered better lightfastness for dyes.

The Bockingford for inkjet is no longer in production? That was one of the first infused papers John Edmund and the infusion expert at the background had a hand in. I actually could not see much difference in the results between the plain Bockingford and the infused.

The Biotop 3 that I use is for design students that need a semi offset quality prop.  I do not use it for longevity projects etc. There are more non-inkjet papers I use for similar tasks. Have to make some scans but this is not the Nirvana of inkjet printing you will see. It is not the Mondi BIO TOP 3® high-speed inkjet type that is more aimed at inkjet printing. Felix Schoeller has a range and you will find Scandinavian paper research PDFs aiming for that quality too.

For that matter, years ago I did coat Arches Velin with a (silkscreen) coating made by Marabu for CDs to be printed. UV curing coating, I think Marabu sold that coating to a Japanese firm later on. The image quality became better than the uncoated Arches gave but the image still had little wetting resistance.


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Met vriendelijke groet, Ernst

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




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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #56 on: March 11, 2014, 05:00:14 am »

The Iris dyes on uncoated Arches were more light resistant than on the inkjet coated Hahnemühle. It is not the paper porosity but the coating porosity etc that had an effect. At that time the pH grade of the inks and the pH of the media was considered to play a role on that aspect. Dyes + cotton could build on textile coloring technology and did so to a degree. Swellable paper was the other direction that delivered better lightfastness for dyes.

The Bockingford for inkjet is no longer in production? That was one of the first infused papers John Edmund and the infusion expert at the background had a hand in. I actually could not see much difference in the results between the plain Bockingford and the infused.

The Biotop 3 that I use is for design students that need a semi offset quality prop.  I do not use it for longevity projects etc. There are more non-inkjet papers I use for similar tasks. Have to make some scans but this is not the Nirvana of inkjet printing you will see. It is not the Mondi BIO TOP 3® high-speed inkjet type that is more aimed at inkjet printing. Felix Schoeller has a range and you will find Scandinavian paper research PDFs aiming for that quality too.

For that matter, years ago I did coat Arches Velin with a (silkscreen) coating made by Marabu for CDs to be printed. UV curing coating, I think Marabu sold that coating to a Japanese firm later on. The image quality became better than the uncoated Arches gave but the image still had little wetting resistance.


--
Met vriendelijke groet, Ernst

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






That's what I meant - microporous coatings on paper. All paper is porous anyway.

Bockingford is only available up to 13x19" size, and not at all in roll form. Not that it's particularly impressive, anyway.

Would you consider the colour images you're getting with the Z3200 and BioTop paper to be photo quality? What have you used successfully for longevity work?
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Ernst Dinkla

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #57 on: March 11, 2014, 06:34:15 am »


Would you consider the colour images you're getting with the Z3200 and BioTop paper to be photo quality? What have you used successfully for longevity work?

No, not photo quality, something between magazine and newspaper quality. For B&W there is less lost. It is possible to get close to the old rotogravure B&W book printing that I always liked. An old fashioned taste though.
 
What Aardenburg-Imaging showed as lasting; HM + Canson paper qualities + Z3100 and Z3200 Vivera pigments and more and more used with protective sprays. That does not cover the mechanical issues like abrasion and coating bond. Something I was well aware off but have no answer on right now other than framing behind glass.

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Met vriendelijke groet, Ernst

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

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shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #58 on: March 11, 2014, 08:21:14 am »

No, not photo quality, something between magazine and newspaper quality. For B&W there is less lost. It is possible to get close to the old rotogravure B&W book printing that I always liked. An old fashioned taste though.

That's disappointing. I would certainly classify Piezography or MIS black-and-white inks on Arches or Fabriano paper as being photo quality - they're equal to any platinum print I've seen, with a Dmax similar to coated matte paper. But, obviously, colour is more difficult, being that you need to widen the gamut as well as increase the density, and you have the total ink limit to contend with as well.
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Ernst Dinkla

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #59 on: March 11, 2014, 09:43:00 am »

That's disappointing. I would certainly classify Piezography or MIS black-and-white inks on Arches or Fabriano paper as being photo quality - they're equal to any platinum print I've seen, with a Dmax similar to coated matte paper. But, obviously, colour is more difficult, being that you need to widen the gamut as well as increase the density, and you have the total ink limit to contend with as well.

There is a range of ordinary inkjet papers with thin coatings from companies like Felix Schoeller, Mitsubishi, etc that certainly create color photo quality prints. The gloss with dye inks, the matte for both types of ink. The papers you baked in the sun had thicker, more complex coatings than used in the ordinary qualities and the last may stand the treatment better, at least on the coating bond.

Blacks on uncoated papers like Arches with the inks you mention is visibly lower than on coated papers. The Dmax measurements show that too. On Biotop 3 the best measurement shows a 1.5 D, L 20.70, Paul hits at approx L 18.0 ( 1.6 D?) with Eboni on uncoated Arches, Photorag with HP Vivera can get to 1.82 D. It is not just that but bleeding of detail, mottle in gradations etc that count for me. I do not use QTR but an ordinary driver and can not boost the blacks though I doubt that would gain much either given the bleeding. For Platinum/Palladium prints I see Dmax values reported from 1.3 to 1.8.

The surface of the prints made on uncoated paper can be handled far rougher than coated inkjet papers allow. Offset on opposite pages in books is no issue either. A big plus. So yes, what Mark tried to achieve with Hawk Mountain etc could solve other issues too. There is a thing we should not forget though, with pigment inks the gain in Dmax and gamut is by keeping the pigment layer at the top which inevitably leads to a delicate surface.

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Met vriendelijke groet, Ernst

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