Question Knowing when to use unbuffered mats?

[Blackcat]

So I was trying to research when to use unbuffered mats on photos and came across this list. I had never seen one like it so I thought others might not have either and wanted to share it. Also if anyone has things to add to the list I would interested in those items. My other issue is in how to recognize a photo that requires an unbuffered mat. Can anyone help me with that?

Here is the link for the list: http://www.redimat.com/articles/buffered_v_unbuffered.html

 

[FramerDave]

Protien-based materials are sensitive to alkaline environments. So this means anything made of or by an animal, such as:

Silk
Parchment/vellum
Leather
Wool

 

[preservator]

unbuffered board

The sensitivity of protein to acids and bases makes use of neutral support materials a logical option, but not something that is necessary in as many cases as were listed. The PVA used to laminate so many of the boards on the market, today, can render those boards acidic, over time, if there is no alkaline reserve in the paper. Thus, the only turly neutral paper materials are those that have starch adhesive or no adhesive. A sheet of neutral tissue, placed between the board and the matted item, can be a good alternative. Those photo materials that do need unbuffered materials are cyanotype, dye transfer, and chromogenic prints. These are rarely presented for framing.


Hugh

 

[Gilder]

neutral tissue? Can you give us a sample please.
Thank you sir.

 

[preservator]

Neutral tissue

Examples of unbuffered, or neutral pH tissues are; Phototex from Archivart, Hollinger/Metal Edge, Permadure - Unbuffered, from University Products, or Renaissance or Apollo from Light Impressions.


Hugh

 

[Alan Yaffe]

The sensitivity of protein to acids and bases makes use of neutral support materials a logical option, but not something that is necessary in as many cases as were listed. The PVA used to laminate so many of the boards on the market, today, can render those boards acidic, over time, if there is no alkaline reserve in the paper. Thus, the only turly neutral paper materials are those that have starch adhesive or no adhesive. A sheet of neutral tissue, placed between the board and the matted item, can be a good alternative. Those photo materials that do need unbuffered materials are cyanotype, dye transfer, and chromogenic prints. These are rarely presented for framing.


Hugh

\

I was also told egg tempera should be included with protein based media that need unbuffered boards. Is this true?

 

[Shayla]

I'm doing a talk at our local photo club on proper mat
choice and, in my preparations, have come across
this thread. It has a good title for archive searches,
so rather than begin a new one, I'm posting here.

Thanks to you who commented, and although it's
not a photographic item, I'm also curious about what
the answer would be to the egg tempura question.

While we're at is, what do you think of using something
like Alpharag Artcare barrier paper, the thinnest, flopsy
kind, between a more acidic mat and the artwork? I've
had a few people bring in non conservation mats they
were determined to use, and I put that between to at
least provide some protection.

 

[Shayla]

Okay, I've just looked through that link list, and
it seems like, because it would be hard to tell
which is what sort of technique, if we get in an
old photo of unknown printing methods, the
safest bet would be to use an unbuffered mat.
Are there any times that using such a mat would
be a detriment?

 

[Jim Miller]

...Are there any times that using such a mat would
be a detriment?

The sensitivity of protein to acids and bases makes use of neutral support materials a logical option, but not something that is necessary in as many cases as were listed. The PVA used to laminate so many of the boards on the market, today, can render those boards acidic, over time, if there is no alkaline reserve in the paper.

It may be harsh to say the use of unbuffered boards would be a detriment. They would represent a limitation in the framing, but perhaps one that is worthwhile. Due the the natural chemical reactions that eventually make acid in even the best paper fibers, an unbuffered mat probably would become acidic sooner than a buffered mat. One solution to this potential drawback would be to replace the unbuffered boards every few years instead of every few decades.

I just noticed Hugh's comment about the PVA adhesive used in matboards. In developing the course outline for "The Myth of Acid Free", I learned that nearly all matboard makers, including the two most popular brands, use PVA to assemble the layers of their boards. The only exception I know about is that Peterboro uses starch paste in their boards, not PVA.


I am a satisfied user of Peterboro matboards and an occasional consultant. Peterboro will sponsor "The Myth of Acid Free" at WCAF.

 

[Rob Markoff]

Jim- glad you brought that up about Peterboro and their starch based adhesive.

Another positive tidbit is that their boards are the only boards that are truly recyclable since there is no plastic in their adhesives.

This means all the trimmings in the manufacturing process can be recycled into paper products and not turned into asphalt or paving materials.

 

[Rick Granick]

what do you think of using something
like Alpharag Artcare barrier paper, the thinnest, flopsy
kind, between a more acidic mat and the artwork? I've
had a few people bring in non conservation mats they
were determined to use, and I put that between to at
least provide some protection.

I'm not sure that would be worth the effort and expense, unless you are going to cover the artwork within the window opening, because I believe that, while some acid migrates through the mat's backing paper, it is the deterioration of the pulp material exposed at the bevel which most creates an acidic micro-environment. Back in the olden days we used to see a lot of L.E. prints framed using woodpulp mats with a layer of 1-ply rag beneath the bottom mat, and when you unframe them down the road you still see all the evidence of mat burn.
:kaffeetrinker_2: Rick

This means all the trimmings in the manufacturing process can be recycled into paper products and not turned into asphalt or paving materials.

Does that mean we're going to be seeing more non-conservation paved surfaces?

 

[Shayla]

....Due the the natural chemical reactions that eventually make acid in even the best paper fibers, an unbuffered mat probably would become acidic sooner than a buffered mat. One solution to this potential drawback would be to replace the unbuffered boards every few years instead of every few decades.

So, does this mean that unbuffered mats can eventually be
equal to or worse than buffered mats, as far as acid goes?

 

[Rebecca]

I learned that nearly all matboard makers, including the two most popular brands, use PVA to assemble the layers of their boards. The only exception I know about is that Peterboro uses starch paste in their boards, not PVA.


I am a satisfied user of Peterboro matboards and an occasional consultant. Peterboro will sponsor "The Myth of Acid Free" at WCAF.

What about Rising (my personal favorite)?

On a different but kind of related note, I've never seen PVA cause any acid burn type damage to paper, it just soaks into the fibers to form a horrible irreversible lump. In fact, when I've seen it used to glue paper to nasty chipboard etc. it actually forms a barrier to protect the paper from the stuff in the chipboard. Not that I'm recommending it, but it might not be such a terrible thing in matboard. And then there are PVA's and PVA's. I would think (hope?) that those used to make quality matboards would be of the more benign variety like Jade 403.

Also on a different but kind of related note, paper made of good quality materials (eg rag, no chlorine bleach, no heavy alum-rosin size) like pre 1790 ish papers, may have relatively low pH (in the 4-5 region) but still be in very good condition.

The deacidification buzz was/is mostly about inherent vice papers made from unpurified woodpulp, and/or papers damaged by chlorine bleached pulp and very acidic sizes.

 

[Jim Miller]

So, does this mean that unbuffered mats can eventually be equal to or worse than buffered mats, as far as acid goes?

Yes. Consider that all cellulose fibers can generate acid over time. The high-alkaline buffer impedes that process, but eventually the acid would be formed anyway. How much time? That depends on environmental factors, aditives, and inherent vices of the paper, but it usually amounts to decades, or possibly even centuries, before it becomes a real problem.

Generally, the chemical conversion process that creates acid in paper takes a long time. If the high-alkaline environment caused by buffered boards would cause problems for an alkaline-sensitive item in the frame, then unbuffered boards should be used. The issue of faster acidification in the unbuffered paperboard could be mitigated easily by replacing the boards before they age to the point of acidity that could be harmful.

From the United States Library of Congress:​

“Fibers made of cellulose chains degrade when exposed to an acidic environment in thepresence of moisture. In this acid hydrolysis reaction, cellulose chains are repeatedly split into smaller fragments so long as the source of acid remains in paper. This acid hydrolysis reaction produces more acid in the process, and the degradation accelerates in a downward spiral.”

For more information:
http://www.loc.gov/preservation/scientists/projects/zeolites.html

http://www.loc.gov/preservation/resources/care/deterioratebrochure.html

A new discovery made in the research laboratories of the Library of Congress shows that, as it ages, cellulose itself generates several acids, such as formic, acetic, lactic, and oxalic acids.
Measurable quantities of these acids were observed to form within weeks of the manufacture of paper while stored under ambient conditions. This research also shows that these acids continue to accumulate within paper as they attach themselves to paper through strong intermolecular bonds. This explains why acid-free (pH neutral) papers also become increasingly acidic as they age.
Acids are formed even in alkaline paper, although in this case they are probably neutralized by the alkaline reserve before they can do any damage to the cellulose molecule.

http://www.conservationresources.com/Main/S CATALOG/What Causes Acids to Be Present in Papers.htm

http://www.conservationresources.com/Main/S CATALOG/Acid Deterioration.htm

http://www.conservationresources.com/Main/S CATALOG/What Can We Do to Protect Paper From Acids.htm

 

[Alan Yaffe]

What makes PVA such a good adhesive is the fact that it is highly acidic and upon drying the acid bonds form long polymer chains giving great bonding. These do become inert for the most part. Over time though acid is given off as Hugh has said via off gassing. I am not so sure this should be ignored. PVA in liquid form starts out at a pH of about 5. Some are a little higher and some a little lower depending on the solids level. I don't think anyone will see art crumbling before their eyes if PVA is used but if you can avoid using it all the better.

 

[Jim Miller]

What about Rising (my personal favorite)?

I don't know, but I guess they use PVA, like most other matboard makers. My understanding is thatPeterboro had to develop an innovative method of using starch paste instead. But they considered the innovation worthwhile, to avoid the acidic tendencies of PVA. Starch paste, as a simpler chemical concoction than PVA, might cost less, as well, but I'm not sure about that.

...The deacidification buzz was/is mostly about inherent vice papers made from unpurified woodpulp, and/or papers damaged by chlorine bleached pulp and very acidic sizes.

Of course, matboards made of cotton and high alpha cellulose fibers from purified pulp do not contain the inherent vices you mention. If this topic expands to include "acid free", "white core", and lower grades of matboards, where those additive and vices are commonly found, then the small evils of PVA adhesive probably would become moot.