Historic moldings can go missing for a variety of reasons, and they’re not always easy to replace. Sure, you can order custom molding knives and pay for custom millwork, but this can be cost prohibitive—especially when only small pieces need replacing. Another approach is to appropriate a technique of the plaster trade. Plaster moldings were not always made in molds; some were “cut” with knives shaped with a profile. Traditionally, plaster could be “run in place” on the wall, using a profile knife to give the plaster a desired shape. The technique, used with plaster, wood filler, or epoxy, works well for re-creating small pieces of missing moldings.
Tools & Supplies
Chemically resistant gloves (some may be supplied in the epoxy kit)
Copy the molding shape by tracing or using a profile gauge, then transfer the shape to a “knife blank” (metal or plastic drywall knives work well) with a permanent marker. Metal knives can be “cut” on a benchtop grinder (wear protective gear), while plastic or wood/Masonite knives can be cut on a scroll saw or jigsaw. For patching voids deeper than ½”, make one knife for the scratch coat (trimming 1/8″ to ¼” off of the leading edge to set this coat back slightly), and one for the topcoat (filing and sanding the edge so it’s a close match to the molding).
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