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How to Repair Plaster Moldings / Mouldings

Getting Your Profile in Shape

How to Repair Plaster Moldings!

by Pamela Cole Harris

If you have wonderful plaster moldings in your home, count your blessings! If you have plaster moldings in your home that seem vaguely reminiscent of the ruins of Pompeii, I have only one thought: “What did you do to deserve this?”. But whatever shape your moldings are in, there are steps you can take to make them look as good as new.

(A word of warning: this is not easy and if you mess it up, I never knew you!):

1. If you have a lot of moldings to replace or repair in a room, consider using polyurethane molding instead. I know it’s not historically correct, but it can look just like plaster and will make your life easier.

2. If you have an older home which has a section of damaged molding, there are two things you can do:

  • Remove the molding and replace it all (See step 1 and take it to heart!)
  • Make a template of mylar to match the molding profile and shape a plaster patch yourself.

3. If the damaged section is over 12 inches long, replace all of the molding rather than repair it. (I repeat, see step 1 and take it to heart!)

4. If the damaged section is less than 12 inches long, use a profile gauge to copy the profile to mylar. (They will know what you are talking about if you ask at your home improvement store. If they don’t, I repeat: see step 1 and take it to heart!)

The mylar needs to be stiffened by being attached to a wood frame (It will look like a picture frame cut diagonally) to keep it stable. Cut the shape of the profile into the mylar which is away from the frame with a coping saw or jigsaw.

5. Fill the section of molding you are replacing with patching plaster. Small pieces of steel mesh can be used to strengthen and support the plaster if necessary.

6. While the plaster is still wet, draw the mylar template over the surface to shape the profile.

7. Smooth the plaster carefully with a sponge, taking care not to destroy the new profile shape.

8. Let the plaster dry before you do your final finishing.

9. Finish and shape the surface with fine grade sandpaper.

10. Paint as desired

There! Take a deep breath! That wasn’t too hard, was it?

Hey, now! What are you doing to that profile gauge?

You just missed my ear! Hey! That’s designer abuse! Laurence Llewelyn-Bowen will hear about this!!!