Hello Ron,
I am the Connecting to Collections Care Monitor for the next two weeks.
It is a common practice to use Mylar or Melinex 516 or an inert polyester film to stabilize paper-based objects in Library and Archives. The condition of the object will affect the choice of whether to encapsulate it or to include an alkaline reserve sheet inside.
If the paper is being completed sealed on all sides (encapsulated), research completed by William Minter and John Baty in 2013 showed that there was not any significant difference between deacidified and undeacidified papers prior to encapsulation. However, it is still recommended to deacidify a paper wherever applicable and possible prior to encapsulation or include an alkaline reserve sheet inside. Additionally, the paper grades that they tested did not show encapsulated acidic sheets degrading faster than unencapsulated acidic sheets in the analysis that they performed. Please refer to the articles below for reference. If the paper is housed in an L-Mylar sleeve that is sealed only on two sides, it is susceptible to environmental elements, and the off-gassing from its degradation will have a way out.
AIC Wiki is a good source of reference material that generally can take you in the right direction. However, I encourage you to reach out to a professional for conservation recommendations.
Reference Articles:
https://www.conservation-wiki.com/wiki/Main_Page
Shahani, C. J. "Accelerated Aging of Paper: Can It Really Foretell the Permanence of Paper." Preservation Research and Testing Series: no. 9503. Washington, DC: Preservation Directorate, Library of Congress, 2005. [Online] http://www.loc.gov/preservation/resources/rt/AcceleratedAging.pdf. Accessed 15 July 2013.
Minter, William and John Baty. 2013. "The Role of Polyester Film Encapsulation - With and Without Prior Deacidification - a Study Using Long- term, Low-temperature Accelerated Aging." Research and Technical Studies Specialty Group Postprints 4. 186-239.
From a paper presented at the AIC Annual Meeting, 2013, in Indianapolis, IN. A summary of the presentation is available through AIC's blog, written by Laura Wahl.
Best wishes,
Luda
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Lyudmyla Babadzhanova (she/her/hers)
Connecting to Collections Care Monitor
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Lyudmyla Babadzhanova
Book Conservator
Center for Jewish History
Brooklyn NY
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Original Message:
Sent: 09-19-2023 10:25
From: Ron Hemenway
Subject: Mylar or plastic sleeves for storing items
I have a question about the use of mylar or plastic sleeves to store items. We at the Rutland Historical Society have been placing fragile documents and pictures in plastic sleaves for over 20 years. We do this for two reasons. One reason is to lessed the handling of the items and two is to help oranize and protect the documents. There are 3 size sleeves we generally use. The one we use the most is a full pocket sheet that can fit a 9 by 11 inch document. The others are a two pocket and a four pocket sheet that is perfect for post cards.
Recently I heard that this might not be best practice for protecting and conserving items. In fact insome cases it might even speed the deterioration of these documents. I wondered if this was correct and what the best practices might be ?
We do place large documents in buffered paper in large and extra large document boxes (except for blue prints). However to do this for every item that we put in the mylar/ plastic sleeves would be extremely time consuming.
A second related question is can you recommend a reference book that details the best practices for conserving documents as well as other historical artifacts. I am doing what we have always done and I recently go to thinking this may not be the best practices. I want to learn and I am mostly self taught.
Oh I also volunteer in the farm museum at the Vt State Fair in Rutland. I have tried to protect both documents at historical society as well the antique farm equiptment down at the farm museum. There is a suprising amount of overlap.
Ron Hemenway
Collections Chair
Rutland Historical Society