Many people believe that "plaster wall repair" is an oxymoron. They feel that plaster walls cannot be repaired.
Repairing Cracks in Plaster
- Using a putty knife or a utilty knife, score the hairline crack to open its edges. This may seem counter-intuitive, but you need to increase the area for the repair compound to stick to. Brush off any loose crumbs.
- With a wide taping knife (of the type used for drywall), smooth a thin layer of joint compound over the cracked section.
- Press paper tape or fiberglass tape into the wet area, along the length of the crack. This is ordinary drywall tape. You don't need to purchase any special plaster repair tape.
- Let dry. Feather joint compound over taped area so that the compound extends two or three inches past the taped area.
- Let the joint compound dry. Lightly sand it down with fine sandpaper to get rid of any bumps or ridges. Don't sand so hard that you dig into the tape.
- Feather a second layer of joint compound, this time extending the edges even farther to about six to eight inches. Let dry. Sand.
- Finally, your third coat of joint compound takes the edges out to twelve inches. Since this is your last chance to get the sanding right, be careful to make it smooth.