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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