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Author Topic: Results of six-month 'window test' on inkjet coatings  (Read 36243 times)

shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #60 on: March 11, 2014, 12:33:40 pm »

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.

Thanks. I had a look at those websites. Unfortunately, it seems that these are commercial-grade papers designed for large-volume printing, not fine art papers. They're certainly not cotton rag, and I doubt they are OBA-free either - if they were, the manufacturers would probably advertise them as such. They may not even be alpha-cellulose or acid-free. Without further information, certainly not something I'd be printing archival works on.

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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.

I've seen 1.7 using Cone inks and a printer with a makeshift platen heater set at 55 degrees. No doubt many matte papers can exceed this. But a lot of other matte papers - particularly the heavily-textured ones - only reach around 1.6.

Where did you see a platinum print with a Dmax of 1.8? It's generally around 1.4, although it can be pushed up a bit more (to around 1.5-1.55) using multiple passes. At least that's out of the ones I've seen.

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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.

That's with dye inks. Pigments, in the cross-sectional micrographs I've seen, all stay on, or very close to the surface. I thought the loss of Dmax and gamut was due to the need to restrict ink load due to dot gain and drying times - accelerating the drying process allows for a greater ink load.

No doubt the surface would be more delicate than with a dye print. But delicate is OK - as long as the surface (and the image) doesn't start disintegrating even without abrasion, just through expansion and contraction of the substrate and minimal flexion.

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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.

The coating-on-paper papers, with no extra layer in between the coating and the paper, seemed to hold up very well -at least when uninked. Unfortunately, inkjet coatings are well known for developing micro-cracks when heavily inked... Still, something like BC Pura Velvet or Pura Smooth seems like it would be a good compromise - great lightfastness, good gamut and physically durable as far as coated papers are concerned.

The Kernewek line of canvas (by Kernow, tested on Aardenburg) look interesting. It's uncoated, unprimed cotton or poly-cotton canvas that's basically been soaked in inkjet receptive coating (so no coating to crack or flake off), has a better gamut and Dmax than most canvas and has very good print permanence too. Unfortunately, it's not paper...

You mentioned that your print results on uncoated paper were somewhere between newspaper and magazine output. I assume you mean in terms of gamut and dot-gain, not in terms of the dot pattern (which tends to be horribly low-resolution in both newsprint and cheap magazines)? Would you say the output is somewhat similar to that of a watercolour painting?
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Farmer

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #61 on: March 11, 2014, 04:13:18 pm »

OK, Shadow.

Yours is a comprehensive test from which direct results can be extrapolated for real life situations and there is no possibility that any of the multitude of factors could be an influence on the results - just the ones you've decided are valid.

I expect you'll now be able to provide us with suggested media life times when mounted behind glass on a wall, right?

You obviously know a lot about this subject and have a scientific background of some sort (or at least a strong interest), so I can not understand how you fail to see that whilst very interesting and possibly a tell-tale of something, these are not results from which useful predictions can be made, nor can you safely draw the conclusions which you are given you have no isolated a numer of the potential contributing factors.

So, I don't know.  It's a good subject, you're obviously well informed and I think there's a lot of value here but I don't get you - you're almost rabid in insisting your results are beyond question and despite some interesting discussion you still draw unsupported conclusions.  I have *zero* reason to want to deny your results - no vested interest or counter agenda.  Maybe you're far too clever for me and I don't get it - I accept that as a distinct possibility on any subject, including those within my expertise.

I said before I thought I sounded overly harsh at times and it wasn't my intent, so I'll bow out now - I don't think I can discuss things with you effectively.

/shrug
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Phil Brown

shadowblade

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #62 on: March 12, 2014, 12:24:25 am »

OK, Shadow.

Yours is a comprehensive test from which direct results can be extrapolated for real life situations and there is no possibility that any of the multitude of factors could be an influence on the results - just the ones you've decided are valid.

I expect you'll now be able to provide us with suggested media life times when mounted behind glass on a wall, right?

You obviously know a lot about this subject and have a scientific background of some sort (or at least a strong interest), so I can not understand how you fail to see that whilst very interesting and possibly a tell-tale of something, these are not results from which useful predictions can be made, nor can you safely draw the conclusions which you are given you have no isolated a numer of the potential contributing factors.

So, I don't know.  It's a good subject, you're obviously well informed and I think there's a lot of value here but I don't get you - you're almost rabid in insisting your results are beyond question and despite some interesting discussion you still draw unsupported conclusions.  I have *zero* reason to want to deny your results - no vested interest or counter agenda.  Maybe you're far too clever for me and I don't get it - I accept that as a distinct possibility on any subject, including those within my expertise.

I said before I thought I sounded overly harsh at times and it wasn't my intent, so I'll bow out now - I don't think I can discuss things with you effectively.

/shrug

Nope.

It's a qualitative test, not a quantitative test, without the intent to predict absolute lifespans but with the ability to predict relative lifespans (which papers will fail before others) and mechanisms of failure.

The issue you kept harping about was thermal effects. I also showed that any framed print exposed to direct sunlight will get a lot hotter than an unframed piece of white paper, which completely dismisses that theory, in that any thermal effects contributing to deterioration of plain, white paper will also be there, and in much greater intensity, in framed, printed paper. If you disregard test results you don't like and which don't fit your preconceptions of reality (namely, your hypothesis that framed prints exposed to sunlight don't get as hot as unframed white paper exposed to sunlight) then you're the one pushing an agenda. So far, you haven't presented a single counter-argument backed by either experimental data or logically-presented scientific theory - when presented with evidence contradicting your 'thermal effects' argument, you've essentially done the debating equivalent of running into a corner and sulking.

Frankly, I'm not interested in how long a print will last in a museum or in the hands of conservators. I'm interested in how to produce a print that can last for centuries in untrained hands and uncontrolled environments. Which means wildly-swinging humidity and occasional exposure to direct sunlight.

Besides, it's both pointless and near-impossible to test any of these factors in isolation. If you test for UV exposure using xenon lamps, you'll heat up the print. If you heat up the print to test for thermal effects, you'll also dramatically lower the relative humidity. And deterioration requires more than any one of these factors. Expose a print to intense UV light in space and it will only slowly fade, since UV light degrades ink by catalysing reactions with atmospheric molecules. Expose a print to swinging humidity, but no UV light or atmospheric pollutants, and it will only slowly degrade, since embrittlement of PVOH-based microporous coatings is based on UV and pollutant exposure.
« Last Edit: March 12, 2014, 12:43:52 am by shadowblade »
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Ernst Dinkla

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Re: Results of six-month 'window test' on inkjet coatings
« Reply #63 on: March 12, 2014, 05:06:23 am »


Where did you see a platinum print with a Dmax of 1.8? It's generally around 1.4, although it can be pushed up a bit more (to around 1.5-1.55) using multiple passes. At least that's out of the ones I've seen.

That's with dye inks. Pigments, in the cross-sectional micrographs I've seen, all stay on, or very close to the surface. I thought the loss of Dmax and gamut was due to the need to restrict ink load due to dot gain and drying times - accelerating the drying process allows for a greater ink load.

You mentioned that your print results on uncoated paper were somewhere between newspaper and magazine output. I assume you mean in terms of gamut and dot-gain, not in terms of the dot pattern (which tends to be horribly low-resolution in both newsprint and cheap magazines)? Would you say the output is somewhat similar to that of a watercolour painting?

http://www8.clikpic.com/platinumprinting/section444277.html and on more sites. I wrote "reports seen", there is no platinum print here and I do not like to compare on memory.

Prints made with pigment inkjet inks on uncoated papers have the pigment particles embedded between the paper fibers, in the sizing, whatever. That makes the prints less delicate, based on sheets lying around here. You will not get a much higher Dmax even if you sacrifice detail and lay down ink with a paper setting for Photorag etc. You might gain Dmax with multiple print runs. Get a flatbed printer then with a hot plate. When you achieve that the pigment will be bare on the surface and be as delicate as it is on coated paper.

No of course not the raster screening of a newspaper image but gamut etc. Between newsprint and magazine print, not cheap magazine. There must be an offset print shop where you can get some sheets Biotop 3 or similar and feed it through the Z3200 you have an eye on. Anyway it is not the paper you intend to use. It was just to illustrate what the quality of a Z3200 + uncoated paper delivers, you wondered about that.

I too have to finish this message exchange, got work to do and keep some time for other threads.

-
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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