[quote="Doremus Scudder"] I use the Seal "BufferMount" (formerly "ArchivalMount") low-temperature mounting tissue. It is also removable by heat. I routinely mount prints that have been selenium toned, many to completeion, and have never noticed a change in image color, or damage of any kind.

Ditto. I have 10 year old selenium toned gelatine silver prints with no discernable degradation on Seal Archival Mount. Still usin' it. Still gonna use it.