Things You'll Need
Concrete bonding adhesive
All-purpose joint compound
Moisture can have a devastating effect on plaster if allowed to linger unabated in a home. As moisture seeps through a wall, it can push your plaster forward, causing a small bubble in the material known as blistering. The only effective method of removing the blister, after dealing with the moisture issue, is to remove the effected plaster and replace it with a patch. Quick to apply and to dry, joint repair compound helps you recreate the plaster surface with a paintable patch that blends in with the surrounding plaster, leaving you with the fine look of plaster that old homes are known for.
Slit the blisters open using the edge of a taping knife. Scrape the plaster covering the blister off the wall with the knife blade and scrape away any loose plaster surrounding the blister as well.
Brush a layer of concrete bonding adhesive over the scraped area. The adhesive will aid in binding the new plaster patch to the old plaster surface. Wait for the adhesive to dry to the point where it loses it's wet look but remains sticky to the touch.
Spread a coat of all-purpose joint compound over the adhesive layer using a taping knife. Apply the compound in an even, smooth layer, tapering out the edge with the edge of the surrounding undamaged plaster. Wait for the compound to dry to the point that it's hard to the touch.
Sand the surface of the compound smooth with a sanding sponge, removing any ridges or high points made with the taping knife. Wipe away the sanding residue with a clean cloth. Apply a second coating of the joint compound over the first to build up a finishing layer. Allow the second coat to dry completely, waiting the manufacturer's suggested drying time.
Sand the compound smooth with a sanding sponge. Feather the edge of the compound patch onto the surrounding plaster, removing the small ridge created from applying the patch. Wipe away the sanding residue with a clean cloth after sanding.
Brush a layer of primer sealer over the compound to prepare the patch for painting. Allow the primer to dry overnight and apply a coat of paint the same type and color as that covering the rest of the plaster surface to blend the patch in with the surrounding plaster wall.