Some vellum books have been stored temporarily in the Hofer space when the RH is too low during the winter months in other storage spaces within Houghton. The Pusey and Lamont stacks are also problematic for winter time RH. If possible it is best to not select them as a permanent storage location. But, if Pusey and Lamont must be used for permanent storage then selecting a phase box to provide compression is the better option. All codex manuscripts with vellum pages are by default always measured for phase boxes. For single leaves, these could be foldered and then put into a phase box with a build-up, or stored in flat boxes in individual folders with some Coroplast sheets or archival corrugated board on top as weight. It is not ideal, but at the collections in boxes and en masse buffer each other more than when they are is smaller groups/out individually for cataloging work.
Avoid processing vellum and parchment in Pusey workspaces during the months of December-February. This is when the RH is below 30% and the physical changes that can happen are irreversible.