Fr. Ed Eherer, C.Ss.R.
I’ve always liked the look of bronze but I know that traditional casting can be elaborate, require special skills and without a proper foundry the task is near impossible. However, because of the development of plastics and polymers, a reproduction with the look of bronze can be achieved easily and at a low cost. This technique is called “cold-casting,” because it doesn’t require the use of molten metal but rather plastic resin impregnated with bronze powder.
I started with a borrowed bronze door plaque from one of our houses. Next, I fashioned a silicone rubber mold with a user-friendly product called OOMOO-30 from Smooth-On.
The original was hot-glued to a piece of foam-core and a simple mold box was built around it (I used a Tupperware sandwich container). Next the 2-part molding compound was mixed and poured onto the original in the mold box. This was allowed to cure for 6-8 hours. The original was removed and the silicone mold cleaned up of flashing.
I next dusted the mold with bronze powder – very little is required to produce the bronze effect. Next, a 2-part plastic resin is mixed up and poured into the mold. This is allowed to set (ideally overnight).
The copy is removed, any remaining flashing is removed and it is buffed to a shine.