how to repair victorian cornicing?

Question

i have an old hallway with original victorian cornicing.

there is a small section about 12 inches long that is damaged, someone suggested using plaster of paris to build it up. but is there a way of creating a mould to ensure that it looks the way it should?

Answer 1

If you go to an art supply house or theatre supply house you can get your hands on a flexible carrageenan based molding compound that is typically used to create molds of a persons face. If you spread that onto an undamaged section of the cornice, let it cure and then covered the exterior with fiberglass and resin before you removed it you would have a mold of the details that you could then use to create the repair, I can think of two techniques for this.

1. Clean the damaged areas to get a strong bond between the plaster and the existing molding. then mix up a batch of the plaster, spread some onto all of the damaged areas to create a bond and then fill your mold with plaster. Press the mold into place, making sure you have any repeating details lined up, then let the plaster cure. Remove the mold, and sand, file, and shape the plaster until it matches the existing surfaces, then prime and paint to match.

2. cut out the damaged section, Make a plaster version in the mold, with wood stringers for support, let the plaster cure, then fit the new piece into the opening, feather the edges between the joints, prime and paint to match.

Or, if the cornice only has running details, no dentil or roping, etc., it would probably be easier for you to simply apply the plaster directly to the molding by hand so that you can shape and feather it during application so that you don't need to spend as much time sanding.

Answer 2

In the time it takes you to make a mold for the cornice, you could repair what you have to. I've used plaster and bondo before for reapirs. Fill in the areas in question, let it dry then sand and form it. It's not a quick thing to do and will require a bit of patience and some skill. You have the rest of the cornice to go from. There are some places that sell manufactured cornice and interior detail trim. But finding something to match exactly what you have may not be an easy task. If you do not want to attempt it yourself, try and track down a wood mill or a local handyman that advertises interior trim. I would make sure and get photos and references before I hire anyone. You don't want more of a mess than you already have. I keep an extensive book of all my previous work along with names and phone numbers of clients for just such purposes. Good Luck.

Answer 3

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