Q: I have an old Victorian with beautiful plaster medallions & crown work how do you fix cracks in detailed work like this?

A: It all depends on how bad they are. If they are just hair line cracks, you have to open them a little bit with a scraper – very carefully. Do not loosen up what is still attached firmly.

Paint the opened cracks with a good oil-based alkyd primer (we recommend Benjamin Moore primer). Do not use an underbody as they have too much sheen; you want something with a dead flat surface for the repair agent to adhere to. Ask for something you can paint latex over! Let that dry thoroughly and then use a good light-weight spackling and fill the cracks completely, trying not to leave too much on the undamaged surfaces. Allow that to dry thoroughly also and then with a fine (100 grit) sandpaper you have to get right in there and sand off everything that doesn’t belong.

Prime again with the same primer and then when it dries you are ready to paint.

If the cracks or chips are more substantial then you may have to do several coats of spackling but there is no need to prime between each coat. Old plaster which has been damaged by water has a tendency to have a powdery surface and you must seal it so that the new plaster will adhere.

If there are large sections of detail missing it will really require a professional’s touch but you can try it if you want. One way is to make a template to match the existing pattern (this relates to crown moldings) out of firm cardboard or masonite, put a large glop of plaster on the cleaned and primed area to repair and then drag the template through the plaster to recreate the original profile. You may have to do this several times to get the hang of it. It will be necessary to go over it to fine tune it as all plasters tend to shrink a little bit when drying. Use spackling for this.

The other method requires having a lot of spare time and entails removing the damaged area right back to the wall and ceiling, and making them good. Use a sawzall or back-saw to trim the edges of what is still good to 90 degrees on both sides of the gap. Then VERY CAREFULLY remove about two feet of the molding which isn’t damaged. Repair the wall and ceiling, clean up the good section of molding, make a mold of it and then cast new pieces to fit in to the repair area. If you need to go to this extent then you’ll need more detailed info on mold making and it might be easier to remove all the existing molding and replace it all with new.