acid-free products
Jun. 18th, 2004 10:39 pm![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
iamthemuffin.livejournal.com posting in ![[community profile]](https://www.dreamwidth.org/img/silk/identity/community.png){kind=small}
craftgrrli work in a frame shop and got a memo today from our corporate office about the difference between "acid-free" and "lignin-free" matboards. it's matboard specific, but the information is just as easily applied to papers and whatnot for those of you who do scrapbooking or anything else where preservation is an issue. just thought i'd pass it along!
"The logical assumption is that 'acid free' boards are entirely free of acid, but that's not entirely true. The wood pulp from which 'acid free' framing boards are made contains lignin, an acidic, organic substance that bonds the wood fibers together. Some lignin is extracted drung most automated paper-making processes, but some is also left behind, which would cause discoloration and embrittlement of the final product. In order to counteract the lignin's harm, a high-alkaline buffer is added to the paper pulp. But as the board ages and the lignin uses up the buffer, the pH value eventually diminishes - past the neutral value of pH 7, and continues further to the acidic side of the pH scale.
"The buffer added to framing boards is proven to be a good defense against acid deterioration for a decade or more, but it will eventually become depleted. As the buffer wears out, the acid from lignin (which was in the paper all along), may cause the board to again become acidic, which could migrate to artwork and cause damage.
"'acid free' is probably not the best term to describe these boards. A better term would be 'temporarily acid-neutralized' or 'acid-delayed'. The highest quality boards for preservation purposes are made from alpha-cellulose: highly purified pulp of wood or cotton, which contains no lignin. Most of these boards are also buffered, to neutralize acids that might migrate from other sources.
"When preservation of an item is key, one should not simply take the term 'acid-free' for granted. Simply because an item is acid-free when it is sold does not necessarily mean that it will always remain that way. For true conservation purposes, the term "lignin-free" indicates the highest quality product."
"The logical assumption is that 'acid free' boards are entirely free of acid, but that's not entirely true. The wood pulp from which 'acid free' framing boards are made contains lignin, an acidic, organic substance that bonds the wood fibers together. Some lignin is extracted drung most automated paper-making processes, but some is also left behind, which would cause discoloration and embrittlement of the final product. In order to counteract the lignin's harm, a high-alkaline buffer is added to the paper pulp. But as the board ages and the lignin uses up the buffer, the pH value eventually diminishes - past the neutral value of pH 7, and continues further to the acidic side of the pH scale.
"The buffer added to framing boards is proven to be a good defense against acid deterioration for a decade or more, but it will eventually become depleted. As the buffer wears out, the acid from lignin (which was in the paper all along), may cause the board to again become acidic, which could migrate to artwork and cause damage.
"'acid free' is probably not the best term to describe these boards. A better term would be 'temporarily acid-neutralized' or 'acid-delayed'. The highest quality boards for preservation purposes are made from alpha-cellulose: highly purified pulp of wood or cotton, which contains no lignin. Most of these boards are also buffered, to neutralize acids that might migrate from other sources.
"When preservation of an item is key, one should not simply take the term 'acid-free' for granted. Simply because an item is acid-free when it is sold does not necessarily mean that it will always remain that way. For true conservation purposes, the term "lignin-free" indicates the highest quality product."
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