I recently began an inventory of our flat file storage cabinets. Each item (maps, posters, large photo copies, etc.) are stored between layers of a wax-paper-like material. This storage system was put in place before I began working at this museum. Does anybody have any idea what this material could be and if it is safe for the objects or should be replaced?
Do you have condition reports for any of those items? Those may offer some clues towards identifying the wax-paper. Otherwise, it may be best to consider replacing especially if the wax-paper shows signs of yellowing.
I spent some time rehousing similar items for a flat file storage unit. I used sheets of 4mil Mylar/archival polyester and buffered paper to interleave between files stored together. Gaylord and Hollinger sell these items. They also offer some helpful tips too.
It could be glassine, which is archival. We sometimes use it to protect the surface of our prints.
Hope this helps!
Please note that neutral glassine needs to be replaced periodically in order for it to remain neutral. If the glassine has yellowed or become brittle from contact with acidic materilas - i.e., the artwork/document that it protects, contact with an acidic material, or just plain age - it needs to be rotated. For this reason it is handy to have a supply or pre-cut neutral glassine available in the storage area.
Good Morning Jacey,
There is a good chance the paper you are describing is heavy weight glassine. It is popular for interleaving because of it's smooth and slippery surface. While I have seen it labelled 'acid free' it does not last long, and is not recommended for long term storage. You can test the paper for acidity using an Abby pH pen, but I err on the side of replacing the mystery paper.
The decision to use something waxy-like makes me wonder if they were worried about smudging--- are any of the materials friable or easily smudge-able such as pencil architectural drawings? For the materials you describe ( posters, copies....) Elizabeth is pointing you in the right direction with mylar (polyester film) and buffered paper (Permalife Bond) for interleaving. Polyester encapsulations are great for handling large items. I would add large map folders fitted to the size of the drawers to keep things from getting inadvertently shuffled, and to give the extra support needed for handling. If you do have large pencil drawings, don't use polyester film, but rather keep them in individual paper folders that keep them from slipping and then group them so that anyone fishing in a drawer for something else is not disturbing them.
A colleague at the Image Permanence Institute advised on a listserv:
"A paper engineer visiting our lab dismissed the idea of chemical additives and said that they accomplished the translucent look by breaking the paper fibers into very small pieces which increased their equilibrium water content and made them more translucent. One of the so-called paper industry “bibles” has a section dealing with butcher paper and glassine and the additives that are put in. either way, I wouldn’t want to store anything of value against a paper with a higher than normal equilibrium water content."
With those possibilities in mind -- unknown additives, or high equilibrium water content -- and the fact that glassine becomes weak and brittle over a fairly brief time span, I think that it might be used for short term wrapping or interleaving, but not for long-term storage.
Thank you all so much for sharing your expertise! This is extremely helpful!
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