'You've learned by now that if you break the Bow Tie off your grille, you should be able to find one on eBay or at a swap meet. But what about that 383 Magnum hood script or Buick GS fender insignia? We're always on the lookout for new and interesting techniques, and we are also always breaking stuff; it's how we have developed some of our repair and restoration skills, which brings us to the subject of casting plastics.
Typically, plastic parts are injection-molded by the manufacturer or an aftermarket company using tooling and machines to which the average person has no access. That, however, is not the case here. Using a few products readily available from Freeman Supply, anyone can mold and cast his own creations or reproduce OE parts that are no longer available. It may sound complicated, but it is really quite simple.
The process is called mass casting, and if you follow a few simple rules, you can cast pretty much whatever you want in the comfort of your own garage. Simple mass casting is used for three-dimensional castings with flat open backs. Think of an emblem without mounting studs. The back side of the cast would remain open, where the liquid plastic can be poured in.
Complex mass casting is the next step in casting, where a single parting line runs through the part connecting two halves of the whole. This requires two molds that fit together, such as a flat, front-side emblem attached to a back side that has the studs attached to it.
Thin-wall casting is used for parts such as armrest bases to replicate the thin walls with a cavity on the back side of the part.
Complex irregular casting is the most difficult of the casting techniques, as this process involves multiple steps and features an irregular-shaped parting line and possibly a hollow or thin-wall section combined into one piece.
We re-created an SS396 fender badge to demonstrate the mass-casting technique using silicone rubber tooling material and clear liquid polyurethane. Using silicone rubber to create the mold eliminates the need for special mold releases, since it acts as its own release agent.
Three holes were drilled in a piece of 11/42-inch MDF wood (particle board) that had been treated with Freeman's wood and plaster sealer so it wouldn't leak. The studs were coated with modeling clay to make sure the liquid silicone did not leak through.
The possibilities are endless with liquid tooling materials. Whether it's creating a custom fender emblem or simply casting a reproduction badge for your resto, plastic casting fits the bill. There are a few guidelines to follow to get the best results from liquid tooling. So read up and get casting.
PARTS DESCRIPTION SOURCE PRICE Rhodia V-330 silicone rubber, 1-gallon kit Freeman Supply $125.00 Freeman FMSC 1090 liquid polyurethane Freeman Supply 130.00 Plast-econ modeling clay Freeman Supply 10.00 Digital scale Local discount store 12.99 Mixing cups Auto parts store 0.50 MDF wood for casting box Lowes 10.00