Unbuffered mat board

Melinda Tennis

MGF, Master Grumble Framer
Forum Donor
Joined
Jul 10, 2002
Posts
834
Location
Lynchburg, VA.
Business
Melinda's
Hi Everybody, I am looking for a source for unbuffered mat board for old B/W photos that have silver in the emulsion. Crescent and Bainbridge show only white. Any source with some good colors? You know browns, beiges, grays.
 
You might check with www.smallcorp.com . They handle Rising boards and have at least one that is unbuffered.

I was unaware that silver gelatin prints needed a purely neutral or slightly acidic environment. I thought it was only the case for Cyanotype and Dye Transfer prints.

Could one of the conservators clarify please?

EDIT: typo

[ 02-26-2004, 12:18 PM: Message edited by: wpfay ]
 
If you are dealing with silver gelatin, unbuffered
is not necessary. It has never been available in
shades other than off white and white.


Hugh
 
Just goes to show that you can't believe everything you read int those tests. Not all of the questions or the answers are right or even relevent to what we do in the real world. :rolleyes: :rolleyes:
 
My understanding is that cellulose likes neutral to slightly alkaline, and protein (e.g.gelatin) likes neutral to slightly acidic.

Silk and wool(protein) fabrics are typically stored with unbuffered tissue.

The archival conservators I know who keep up with photographic conservation recommend unbuffered alpha cellulose enclosures for photos. Exceptions to this are acetate and cellulose nitrate negatives, in the hope that the buffering will help neutralize the plastic's breakdown products.

This being said, they certainly don't suggest that those institutions that have invested in buffered enclosures get rid of them.

Some types of photographs are sensitive to alkaline (I can't, off the top of my head, cite them - I'd follow Wally's lead here, but something in the back of my mind says albumen are sensitive to alkaline too), so the common practice is to use unbuffered materials for all photos. Can't hurt, might help.

Rebecca
 
As Rebecca response suggests, this issue is quite complicated. Remember that if the window mat does not touch the surface of the print, it doesn't matter what type of board is used. Acids and peroxides form volitiles readily, but the same does not seem to be true for calcium carbonate, which is used to buffer mat board. This means that the main concern is contact and not proximity. Since most of the board that is made today is laminated with polyvinyl acetate, the chalk in the board is needed to address the acetic acid that the PVA will eventually produce. Neutral papers and tissues are always safer to use, since they contain nothing but pure cellulose. If one wants to use a colored, buffered board and its window will touch the surface of the photo, a layer of unbuffered paper can be added between the mat and the photo to separate one from the other. Chromogenic prints can be added to the list of candidates for unbuffered board that Wally and Rebecca have mentioned.

Hugh
 
Of course Hugh! I'm thinking "enclosures" i.e. little envelopes, and you all are thinking window mat - i.e. not much, if anything, touching the surface of the photo.

I also didn't know that about PVA being used to laminate matboards -thanks for adding that bit of information. The most widely recommended enclosures wouldn't have any adhesive at all- it's a 4 flap fold-over design.

Rebecca
 
If PVA eventually begins to produce acetic acid, why are we so keen on its use as a substitute for ATG (dust covers, attaching double mats, lining shadowboxes, etc?)

Also, I believe it was John Ranes that mentioned on a recent dust cover thread that he uses Elmer's white glue (PVA) for dust covers. Is Elmers really a PVA glue and, if so, why I am I spending $8.50 for 8 ounces of LIneco PVA adhesive?

The Lineco product certainly LOOKS like Elmer's Glue.
 
Lineco's product has a buffering agent in it...I think Hugh told me it was chalk (CaCO3). I suppose we could get our own Calcium Carbonate and mix it with Elmer's. Maybe a mix of Maalox and PVA :D .
 
From the Conservation Distribution List:


"All PVA glues are fundamentally the same thing: An emulsion of Poly(vinyl
acetate) droplets suspended in a water-based carrier. What differs among them is the molecular weight (degree of polymerization), purity (or, more specifically, the lack of impurities--particularly acetic acid left over from the polymerization), and additives that affect the flexibility of the dried glue film.

Although the carrier liquid might be neutral or alkaline, the dried glue can nevertheless give off acidic compounds, and can therefore become acidic as the glue ages.

I dug around in our old files, and finally found a report (dated 1992) from the Canadian Conservation Institute, entitled in part "An Evaluation of Selected Poly(vinyl acetate) and Acrylic Adhesives", which tested glues
over 5 years of aging (in light and in the dark) for glue film pH, emission of acetic acid vapour by the glue, flexibility, and yellowing. None of the tested glues fared well in all categories. In particular, most of the PVA glues started off acidic, and those that did not became acidic with aging in light.

I am not sure if it is still possible to get copies of this report. Just in case, the full reference is:
Adhesive Testing at the Canadian Conservation Institute - An Evaluation of Selected Poly(vinyl acetate) and Acrylic Adhesives
by Jane L. Down, Maureen A. MacDonald, Jean Tetreault and R. Scott Williams CCI Environment and Deterioration Report number 1603 Written 1992, Third printing January 1994
Published by the Canadian Conservation Institute, then a branch of Communications Canada.
This institute is now under the Heritage ministry; their web site is www.cci-icc.gc.ca

I can't find this publication at that site, although I did find a couple of
other interesting publications...

Kevin Martin
the Papertrail"

I couldn't find the publication either, but did find a review of it in the Abbey Newsletter:


"Adhesive Testing at the Canadian Conservation Institute-An Evaluation of Selected Poly(vinyl acetate) and Acrylic Adhesives, by Jane L. Down, Maureen A. MacDonald, Jean Tetreault and R. Scott Williams. (Environment and Deterioration Report No. 1603) Canadian Conservation Institute, Ottawa, 1992. 30 pp. + 22 tables.

The permanence of adhesives is of central importance for conservation and preservation, but the normal method of testing for permanence by oven aging is inappropriate for most adhesives, since high temperatures cause them to melt or change in other ways not correlated with natural aging. Until the CCI began this project eight years ago, no organization was willing to bite the bullet and start doing natural aging. CCI has been aging the more significant PVA (which they refer to as PVAC) and acrylic adhesives at room temperature, in the dark and under fluorescent lamps, in the form of emulsions and films. This report describes the changes in pH, volatile emissions, embrittlement and yellowing, and contains a vast amount of valuable data. Several adhesives were identified that are suitable for conservation applications, though one should bear in mind that the manuacturers may discontinue or change the formulation of any adhesive at any time without notification, and in fact already have done so with at least two of the eight PVAs identified as suitable.

Those eight suitable PVAs were: Jade No. 403, Mowilith DMC2, R2258, Beva 371, Rabin's Mixture, Elvace No. 1874, Weldbond, and Promacto A1023.

I bet all this doesn't answer your question Ron. :D

Rebecca
 
Originally posted by framah:
Just goes to show that you can't believe everything you read int those tests. Not all of the questions or the answers are right or even relevent to what we do in the real world. :rolleyes: :rolleyes:
Melinda: you're mostly right. The PPFA Recertification class advises that unless the the alkaline-sensitivity of the photo is known, it is better to use an unbuffered, pH-neutral board, which can cause no harm, than to risk possible damage from a high-alkaline, buffered board.

Framah: "Those tests"? What tests?

The whole point of the CPF exam & Recertification class (not a test, by the way), and presumably other framing exams, is to ask the right questions and give the right & relevant answers for real-world framers.

So, if you know of any inaccuracy or irrelevance in a framing exam, please point it out to those who produce it. I'm sure they would appreciate your help.

I can't speak for FATG or any retailer who tests its employees, but I know from personal experience that every word of every question for PPFA's CPF exam is carefully reviewed several times before it actually makes it to the exam, and the entire exam is reviewed every few years.

Jim Miller, MCPF, GCF
Chairman, PPFA Certification Board

[ 02-27-2004, 03:08 PM: Message edited by: Jim Miller ]
 
Thank you, Rebecca, for your <strike>exhausting</strike> exhaustive response to my question.

Since my workshop is wide-open, I decided I'd rather not have a bottle of Elmer's Glue sitting on my work bench, so I think I'll stick with the Lineco glue.

Next time somebody complains about the cost of framing, I can pick up my little bottle of PVA and say, "Do you have ANY idea what a bottle of this costs???"
 
Back
Top