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Author Topic: Best practices for long term prints conservation.  (Read 550 times)

MariC

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Best practices for long term prints conservation.
« on: May 08, 2018, 01:27:45 PM »

I have carried out a little bit of research about whether buffered or unbuffered interleaving paper should be used for proper long term conservation of cotton rag pigment prints and contrary to usual, the advice given on the forum (searching through the last few years’ posts) seems to contradict my findings. Even more interestingly the consensus on the forum seems to be quite consistent, which made me think that I might be missing something. Hopefully this post will see some interesting contribution from those who are more knowledgeable about conservation.

To provide a starting point I will summarize both what seems to be the consensus on the forum over the years, and what I found on the net.

Forum consensus: “unbuffered”
This came from posts referencing a conservator from the Baltimore Museum of Art (post by Scott Wald); Epson email support regarding Exhibition Fiber (post by LynnNoah); and quite a few others which didn’t mention their source so I would catalogue those as (based on experience).


Archivalmethods: “buffered”
This is from their site:  “Some suppliers of archival products are providing confusing information about the use of un-buffered boards and papers with photographic materials. Black-white and color photography (both conventional and digital output) should have mounts or enclosures made from buffered paper. This is the recommendation from the latest ISO document 18902, “Photographic Films, Papers Filing Enclosures”. The only items that need matting or storage in un-buffered papers are cyanotypes (architectural blue prints) and protein based textiles. ISO18902 is available at www.ansi.org.”


Gaylord: “buffered” (given that cotton rag is a cellulose fiber rather than animal protein...)
This is from their site: “Cellulose fibers such as cotton, flax, linen and jute, as well plant-based specimens, can be stored in buffered material. Storing cellulose artifacts in buffered materials will protect against migrant acidity from the artifacts.
Any artifacts that contain animal proteins are best stored in unbuffered material. Protein-based materials include wool and silk, as well as animal-based natural history collections, leather-bound books, and textile details such as pearls. Also, many archivists prefer to store albumen prints and cyanotypes in unbuffered material.“

While I have cited only these two suppliers, the gist seems to be the same (that is, use buffered for cotton based and photographic prints in general). Based on this information, usually I would go for “buffered” without hesitation, especially considering than Hahnemuhle Photo Rag is “calcium carbonate buffered” (according to the specs sheet) which might make it even a better candidate (my guess) but the fact that over the years there were several posts advising to use unbuffered material for pigment prints and "none" about buffered made me think this might be an interesting post to start.
 
As mentioned, hopefully this post will see some interesting contribution from those who are more knowledgeable about conservation.
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Ernst Dinkla

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Re: Best practices for long term prints conservation.
« Reply #1 on: May 09, 2018, 05:24:03 AM »


 
As mentioned, hopefully this post will see some interesting contribution from those who are more knowledgeable about conservation.

Not really an expert on this but 20 years reading stuff on this chapter. Most of the examples you cited are of the non-inkjet type and refer to the substrate, not the inks.  The Epson Exhibition Fiber is a paper best avoided anyway, it has longevity issues of its own, check the Aardenburg Imaging tests for it, paper white shift in time.

With inkjet pigment inks on buffered art papers like Hahnemühle's range of art papers I think acid free or buffered tissue paper is adequate. Most serious printmaking is done with inkjet pigment inks these days.

With dye inkjet inks on buffered papers the print results were already less predictable due to the variety of dye chemistries used and I doubt acid, neutral or buffered tissue papers will solve that. Some dye inks proofed to have better longevity on straight cotton papers than on buffered papers. On papers with gelatine/PVA surfaces (gloss/satin mainly) these dyes lasted longer as gas fading had less an influence. Epson, Iris, Ilford Archive, Lyson inks reacted all differently with all the papers mentioned. All gave less longevity than today's pigmented inks can achieve on buffered and plain cotton papers. Waterfastness also very limited. Inkjet dyes at that time were either borrowed from the photographic dye chemistry or textile dye chemistry, with different pH grades and different bonds to the substrates. Glossy/satin swellable gelatine/PVA coated inkjet papers are rare today. Depending on the hydrolysis grade of the polymer interleaving papers could get stuck even when stored in dry environments.

There is quite a difference between the finished chromogenic print with color dye layers separated from one another and their polymer coating hardened in the development process if compared to inkjet dye prints made on swellable gelatine/PVA coatings where several color dyes are mixed within the coating and in contact with one another, coating more prone to humidity issues too.

Today's better dye inks need their compatible microceramic papers to achieve the better longevity than the older dye ink types could deliver. Mordants in the papers to suit the dye inks. The dye ink chemistry is a hybrid of pigment particles and dye colorant in a sense, polymers more crosslinked to clusters than the old dye inks had. Gelatine in and on the papers must have been replaced by PVA in almost any paper now I guess so the animal etc issue is no longer there. The main task of PVA is to bond the coating and less that of embedding the dye ink, microceramics taking over that role. I have no idea what the resulting pH grade of prints like that is but that should tell which kind of interleaving paper should be used

Using acryl based protection sprays on prints may be a good first step for archiving. Interleaving paper will then interact less in a chemical and physical sense with paper and ink in the print and reduce friction issues where it is intended for in the first place.


Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots
« Last Edit: May 09, 2018, 09:24:49 AM by Ernst Dinkla »
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MariC

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Re: Best practices for long term prints conservation.
« Reply #2 on: May 09, 2018, 09:04:11 AM »

Hi Ernst,

Thank you for such a wonderful reply, it was quite an interesting read!

I actually had (as you immediately noticed) left the inks (pigments/dye) out of the equation. Given their proven superiority regarding archival properties, I had given for granted that the discussion would rotate more specifically around pigment prints, but I do realize now that given all the different processes still used now (without even considering "legacy" processes), this becomes an even more complex issue.   

When you say, "With inkjet pigment inks on buffered art papers like Hahnemühle's range of art papers I think acid free or buffered tissue paper is adequate."  Do you meant that both unbuffered Ph neutral (what you mentioned as acid free?) or Buffered tissue paper would be adequate in your opinion for piment prints on buffered papers like Hahnemühle Photo Rag, or am I interpreting it wrong? Thanks

Also, would may be Melinex (archival polyester), be the safest choice of them all, since its considered both acid-free and inert?

By the way SpectrumViz rocks!

« Last Edit: May 09, 2018, 09:14:34 AM by MariC »
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Ernst Dinkla

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Re: Best practices for long term prints conservation.
« Reply #3 on: May 09, 2018, 09:33:47 AM »

Hi Ernst,

Thank you for such a wonderful reply, it was quite an interesting read!

I actually had (as you immediately noticed) left the inks (pigments/dye) out of the equation. Given their proven superiority regarding archival properties, I had given for granted that the discussion would rotate more specifically around pigment prints, but I do realize now that given all the different processes still used now (without even considering "legacy" processes), this becomes an even more complex issue.   

When you say, "With inkjet pigment inks on buffered art papers like Hahnemühle's range of art papers I think acid free or buffered tissue paper is adequate."  Do you meant that both unbuffered Ph neutral (what you mentioned as acid free?) or Buffered tissue paper would be adequate in your opinion for piment prints on buffered papers like Hahnemühle Photo Rag, or am I interpreting it wrong? Thanks

Also, would may be Melinex (archival polyester), be the safest choice of them all, since its considered both acid-free and inert?

By the way SpectrumViz rocks!

I expect that the buffer in the inkjet paper itself is enough to compensate for acidity that may occur given the interleaving medium is not acid itself. Which also addresses the archival PET materials used as envelopes for prints. I think a slightly matte version of them is preferred to overcome gloss print adherence.  I have seen polycarbonate film, Lexan B35, used as well for that.

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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MariC

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Re: Best practices for long term prints conservation.
« Reply #4 on: May 09, 2018, 09:52:54 AM »

Thanks Ernst.
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