To repair a plaster ceiling, you can follow these steps:
1. Remove the damaged plaster by scraping it away with a putty knife or cutting it out with a utility knife.
2. Seal the water damage by drying the area and removing any loose particles with a shop-vac and a stiff nylon brush.
3. Repair the plaster by applying joint compound with a trowel and pressing insect screen into it to reinforce the patch.
4. Apply a second coat of joint compound after the first one dries and smooth it with a trowel.
5. Sand the repaired area and touch up paint as needed.
Another tutorial suggests that you should screw plaster washers to ceiling along and around cracked area; be sure to drive screws into wood lath above. Use trowel to spread joint compound onto ceiling, covering the repaired area. Press insect screen into wet compound; smooth flat with trowel. Allow joint compound to dry at least 24 hours.
