We're in the process of restoring a historic home built in 1851. Much of the plaster we've uncovered thus far is in pristine condition (looks like milk glass!), but the finish plaster is soft in a couple of rooms (although deeper layers are solid in most areas). After removing the soft coat & before papering or painting, I wondered if we could prime the walls with a fiberglass product (applied this with a roller onto our basement walls a few years ago to bond the surface), rather than having finish plaster reapplied? Even if we don't redo the walls in our lifetimes, we want to know the repairs we make now will endure. We plan to hang wallcovering (heavy paper or fabric-backed) in most rooms, and paint ceilings/some walls. I know walls should be sized before hanging wallcovering, but what type of preparation should be done before painting plaster that has never been painted? Has anyone had experience using the fiberglass product in this type of application, either to replace the finish coat of plaster or to stabilize plaster walls?