Originally posted by fortuna:
while waiting for the mylinex to arrive, i did more research and found that encapsulation can speed up acidic conditions. now i'm wondering if i should do the encapsulation, place a piece of buffered paper behind the onion skin inside the encapsulated package, or tell the client that i am revising my suggestion and not encapsulate at all...
An encapsulation mount can intensify chemical damage only for contaminants that are sealed into the mount. That is more of an issue for a truly sealed encapsulation mount, made by fusing the Melinex pieces' edges together using a special machine. Conservators sometimes have that capability; framers rarely do.
In cases where the paper being mounted is loaded with lignin or other chemical contaminants, especially when the edges of the mount will be fused together by a conservator, conservation treatment before mounting is recommended.
Other, less-tight mounting methods are susceptible to migration of chemical contaminants from outside the mount. So, chemically speaking, there is no perfect mount.
The non-invasive, reversible, almost-airtight encapsulation mount is often better for preservation than other mounting methods when both sides are to be visible, or when the item to be mounted is very thin, supple, or fragile.
The "surface encapsulation" Rick described seems appropriate here. I call that an "overlay" mount. It is like encapsulation, but alphacellulose board is used with a clear film overlay, instead of using two pieces of clear film. That mount is better only when the back may be covered, of course. The board's surface texture provides more holding power than a slippery piece of clear film would provide.