Decorated plaster walls are a vulnerable part of completed structures. The paint decoration often extends to the woodwork. In rare circumstances when painted walls are not appropriate for display we recommend using an archivally-acceptable, reversible procedure to cover them, one which will not damage the historic paint and leave them for later generations to enjoy and study.
Untempered Masonite ¼” thick 4’ x 8’ Masonite is available or can be ordered from local contractor supply houses for @$25/sheet. This untempered Masonite does not contain oils or resins that tempered Masonite and wall board have that will react with the historic painted surface. Cut Masonite to fit snugly within the moldings of the room so it basically becomes a ‘liner’ for the room, much the same as dry-walling the room.
After fitting the pieces, lightly sand the edges to get rid of any furry roughness, then prime BOTH sides with at least 1 coat of either lLiquitex Gesso or 100% acrylic latex primer sealer paint. Let painted surfaces cure ( reach optimum hardness) for a minimum of 24 hours up to a week, depending on humidity in air. During curing process the gas evaporates from acrylic paint.
Using a clear adhesive silicone caulk at top and bottom edges of wall, ‘hang’ the Masonite. When the two pieces of Masonite are in place next to each other the vertical seams can be filled with elastic water based caulk (non-silicane or paintable). Immediately clean up the seam with a damp cloth. This elastic caulk will fill in the seam of the two pieces of Masonite butted together. It doesn’t actually dry and will remain flexible so seam will not crack. If you use drywall paste the seam will crack. It may be necessary to use a nail at the seam of long spans to prevent buckling. Try and strategically place the nails so it doesn’t interfere with decoration underneath.
The butted Masonite seams should be immediately wiped down with a damp cloth. If you use paintable elastic caulk, be sure it does not have silicone in it. Taping the seam would leave a bulge because the edges of the Masonite are not tapered.
Putting an additional barrier between the primed masonite and the wall paintings, something like Japanese tissue, which could be attached to the masonite with dabs of B-72 or other neutral acrylic would keep the walls from being in direct contact with the gesso. It is NOT recommended that the Japanese tissue be attached directly onto the walls, only if there is severe flaking paint would that be an appropriate approach.
Wall treatment can proceed from here.
The use of 100% acrylic primer sealer on the Masonite wall creates a great bonding surface for either paint or wallpaper. It has been suggested that a tiny window could be cut in the Masonite to visibly document decorated wall underneath. This obviously is up to the homeowner or contractor but certainly would provide a visual verification to the curious.
This relatively inexpensive procedure retains the wall murals for the historical record and for the next owners of to enjoy if they choose. By doing this the artist’s intent, the history of the home and the painting’s historical value to the town will be left in tact. The fact that the walls are documented in the library of the PWP will also allow future generations to enjoy them if desired.
Removal of the walls, even if reinstalled into another house, removes them from their original context and will leave them in jeopardy if the next owner dislikes them. With an insecure future, the murals are subject to loss.