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Author Topic: Lumachrome process?  (Read 2318 times)

Wayne Fox

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Re: Lumachrome process?
« Reply #20 on: January 11, 2019, 05:31:59 pm »

To me it sounds like they are using Pictorico Pro Ultra Premium OHP Transparency Film (or something similar), then laminating that to a ďwhite RC paper baseĒ (basically something like unprinted but processed photo paper. I assume they could use some type of metallic paper for this backer if they want that look). This would make sense if they print the image in reverse then mount the inkjet coating to the paper so the bond to the acrylic is the backside if the film.  One concern I have is the durability of an inkjet receptor coat and ink bonded directly to acrylic, and even though Iíve had great results, there really isnít a good way to test how the bond will hold up. I have several  that are more than 5 years old showing no issues, so it seems the bond is holding up well.

Sounds like a slightly convoluted process for something that is actually much more straight forward (unless for some reason they are bonding that sandwich to the acrylic with Diasec / silicone).  I have face mounted hundreds of prints, both chemical as well as inkjet, and I have seen their prints that are being sold by some photographers in a couple of art festivals I have attended. to me the secret to the final result is simply the fact thatís itís face mounted.  I havenít seen any images they have made that I thought offered anything other than what face mounting other products offer.

But Iíll admit Iíve never compared their process side by side. I can understand their claim that side by side they look better than the fujiFlex versions, but that to me is easily explained in the increased gamut, dmax, and detail resulting from using a high end inkjet printer vs chemical photo paper. But why would this be better than directly mounting a quality inkjet print.
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dgberg

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Re: Lumachrome process?
« Reply #21 on: January 11, 2019, 06:23:36 pm »

Thank you Wayne
A great explanation from a very expirenced and valued member.

Ernst Dinkla

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Re: Lumachrome process?
« Reply #22 on: January 12, 2019, 06:22:28 am »

Actually, the American Institute of conservation has put together a good video on this topic:  https://www.youtube.com/watch?v=bq80xpKzl-w&t=11s

Also, Ernst, matt prints from inkjets are easier to work with when using the Diasec method where as luster or glossy need to be laminated with a film first. Wayne had asked this question in another post a few years ago and never got a response from Miranda Smith, but she explains the process here: https://aiccm.org.au/sites/default/files/SMITHPaper.pdf

[Because you seem familiar with them in the past, why do you suppose they're using a rather gooey silicone process instead of a rolled adhesive?]
I found the patent for Diasec online and along with Ernst's link it explains a lot. I spent a few hours researching yesterday :)

I was not aware of that research. My gut feelings are that Mark McCormick will shoot big holes in the results of the AIC research, especially the fast fading objective of the MFT approach and the limited use of patches (for example a grey area can be a mix of many or very few colorants) and by that not very representative for all the inks used in the print. Little is said about OBA content in papers but the paper area result with Endura will be related to that. Using light without UV does not eliminate the effects of light on OBA content in papers; short term, long term and the dark storage effect. What is shown are mainly dye colorant tests; chromogenic, bleached dye photo papers and dye on inkjet paper.  It will be interesting to see what remaining acetic acid in face mounting does on the long term. Oxidising by gasses like oxygen and ozone may be reduced in face mounting and lamination, the chemistry of the glues and their interaction is not brought to daylight yet. Anyway restoration of any laminated or face mounted print remains an issue how well they stand time.

Getting old, you are right that the lamination is done on the inkjet RC papers before Diasec face mounting and not on the matte papers, used to write that correctly in the past.  BTW interesting that the AIC research mentions that the lamination peels off easier from the chromogenic RC papers than from the RC inkjet papers, the remark that the inkjet has no coating is wrong though. I think it may have more to do with the age of the laminated prints.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots

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Ernst Dinkla

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Re: Lumachrome process?
« Reply #23 on: January 12, 2019, 06:41:59 am »

To me it sounds like they are using Pictorico Pro Ultra Premium OHP Transparency Film (or something similar), then laminating that to a ďwhite RC paper baseĒ (basically something like unprinted but processed photo paper. I assume they could use some type of metallic paper for this backer if they want that look). This would make sense if they print the image in reverse then mount the inkjet coating to the paper so the bond to the acrylic is the backside if the film.  One concern I have is the durability of an inkjet receptor coat and ink bonded directly to acrylic, and even though Iíve had great results, there really isnít a good way to test how the bond will hold up. I have several  that are more than 5 years old showing no issues, so it seems the bond is holding up well.

Sounds like a slightly convoluted process for something that is actually much more straight forward (unless for some reason they are bonding that sandwich to the acrylic with Diasec / silicone).  I have face mounted hundreds of prints, both chemical as well as inkjet, and I have seen their prints that are being sold by some photographers in a couple of art festivals I have attended. to me the secret to the final result is simply the fact thatís itís face mounted.  I havenít seen any images they have made that I thought offered anything other than what face mounting other products offer.

But Iíll admit Iíve never compared their process side by side. I can understand their claim that side by side they look better than the fujiFlex versions, but that to me is easily explained in the increased gamut, dmax, and detail resulting from using a high end inkjet printer vs chemical photo paper. But why would this be better than directly mounting a quality inkjet print.

I miss the Iridium particles part in your explanation. There will not be any Iridium in that sandwich (way too expensive) but I think they refer to mica nano particles covered with a metal or dye to yield a pearlescent effect. Often the names of that kind of pigments refer to iridium that can have that effect too.

An inkjet paper that is named like that;
https://www.rauch-papiere.de/en/products/photography-and-fineart/mediajetr-photographersline/mediajetr-sip-260-silver-iridium-pearl/

So  one of the papers like that but face mounted as I mentioned in the first reply in this thread.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots
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Wayne Fox

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Re: Lumachrome process?
« Reply #24 on: January 12, 2019, 11:31:19 pm »

I miss the Iridium particles part in your explanation. There will not be any Iridium in that sandwich (way too expensive) but I think they refer to mica nano particles covered with a metal or dye to yield a pearlescent effect. O
Yeah, sort of marketing speak (like the whole process) my best guess is whatever ďiridiumĒ there  is in the RC paper base that they are using. 
« Last Edit: January 13, 2019, 02:07:48 pm by Wayne Fox »
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mearussi

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Re: Lumachrome process?
« Reply #25 on: January 13, 2019, 10:02:45 am »

According to their web site it seems like nothing more than transparency film laminated to acrylic in the front and a white base on the back, similar to printing on glass with a backing.

http://www.nevadaartprinters.com/fujiflex-acrylic-photo-prints

Given this, how then is their process different from just printing on white film with face mounted acrylic?
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John_Harris

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Re: Lumachrome process?
« Reply #26 on: March 26, 2019, 12:06:40 pm »

Greetings all!  I'm new to this forum - subscribed so I could respond to this post and add some clarity.
First a bit of background, so you know I'm not just blowing smoke out my backside.
30+ years in the fine art printing world and full disclosure: I work for the only North American facility who currently holds a Diasec license - Reed Art & Imaging.
Some questions I cannot answer due to contractual agreements, but I can clear up some questions along with adding some clarity to some mis-understandings.

NFAP states on their website they use a silicone adhesive. This statement alone does not mean they use a silicone gel. Silicone is also used in several pressure sensitive adhesive films (hereout referred to by me as PSAs). There is much ambiguity on their site, likely in effort to protect the star of their show and their marketing leverage.  I certainly won't wrong them for that.

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Because you seem familiar with them in the past, why do you suppose they're using a rather gooey silicone process instead of a rolled adhesive?

The advantages of using a PROPER silicon gel are numerous, and you can check Reed's website for more detail, but here's a semi-brief outline:
Once cured the silicon remains very flexible, protecting the presentation from edge separations, tunneling, snowflaking, etc.  These are well known issues that occur with PSAs.

UPS data states that their trucks can reach summer time temps up to 130įf.  The expansion of a 48" acrylic going from 70į to 130į is approx 1.4". This expansion along with the softening of PSAs can cause separation - ruining a print before it arrives at the gallery or the buyer's home.  And yes, acrylic is sensitive to humidity and will expand and contract with such changes.

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I found that originally, at least for the Diasec method, they used Gurisil No. 575.0 as the adhesive. Personally, all proprietary talk aside, I believe that any current optically clear, uv-resistant, vulcanizable silicone would work for face mounting.

Not quite. UV-resistance is not enough. There are several knock-offs using UV-resistant gel that is yellowing after a few years.  The formula must be specific, not just for the gel but other proprietary ingredients used in the process. There is more to doing it properly than just squirting on some gel and going to town.

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It will be interesting to see what remaining acetic acid in face mounting does on the long term.

After curing the silicon is completely inert and pH neutral. The semi-permeable nature of acrylic allows the acetic acid to outgas. Diasec has been around for 50 years and thus far there have been zero indications of acid damage on any prints.  How the chromagenic print is handled in process and post process are bigger concerns. 

Quote
Yeah, sort of marketing speak (like the whole process) my best guess is whatever ďiridiumĒ there  is in the RC paper base that they are using.
Quote
According to their web site it seems like nothing more than transparency film laminated to acrylic in the front and a white base on the back, similar to printing on glass with a backing.
Quote
Given this, how then is their process different from just printing on white film with face mounted acrylic?

NFAP's website states that the iridium is in the transparency layer. With a white poly backer. "thanks to the transparency layer that is infused with iridium particles and is encapsulated in a layer suspended between the white poly surface and Acrylic." 
My personal estimation is that the poly is something akin to fuji flex or an inkjet flex. The result would be two pearlescent layers - the trans and the backer, contributing to the "depth" that people speak of.  by having a few mils of PSA between the two could result in some shadowing that would also add to the 3D effect touted in their marketing.
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dgberg

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Re: Lumachrome process?
« Reply #27 on: March 26, 2019, 01:55:36 pm »

Thank you John, and welcome.

Alistair

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Re: Lumachrome process?
« Reply #28 on: April 19, 2019, 12:37:53 am »

I miss the Iridium particles part in your explanation. There will not be any Iridium in that sandwich (way too expensive) but I think they refer to mica nano particles covered with a metal or dye to yield a pearlescent effect. Often the names of that kind of pigments refer to iridium that can have that effect too.



Met vriendelijke groet, Ernst



Probably something like this:
https://www.merckgroup.com/en/brands/pm/iriodin.html

Not sure if a transparency is available pre-coated with such a material or whether NFAP are applying it themselves. If they are printing the transparencies themselves using inkjet then I can see that sharpness and reasonable color could be achieved with this method. The difficult part is determining the right silicon gel to use. John talks of "proper" silicon gel, whatever that actually means!
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Alistair
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