Mold Making:

Plug Building With Other Materials

The following list cites other materials that can be used when constructing plugs designed for specific applications as well as units that have been produced with these various materials.

1. Plaster & Hemp: Plaster and hemp (rope) material can be mixed to form a pourable concoction. The plaster is reinforced by the hemp material. This process works well when a quick splash is required in establishing rough design or rough dimensions in the least amount of time. It can be applied eight to ten inches thick in one application.

For instance, to determine the rough dimensions of a wheel well on a truck or the curvature of the side wall of a truck, this plug template would be both quick and inexpensive. The surface of the plaster will remain pitted and porous but will exhibit dimensional stability. For a quick mold, we could build the first three layers of laminate over the plug as though we were building a mold, and then back up the laminate with this concoction. This would allow a "one-off" temporary glass mold.

2. Foam Blocks: This is usually a low-density foam carved to a specific shape, with consideration being given more to shape than to dimension. One use might be the forming of a statue or a logo that requires a large degree of artistic design and self-expression.

To produce a mold from a foam plug, apply a coating after the design has been established. This coating could also be polyester resin and a fiberglass, laminate or polyester primer.Usually this kind of plug will be good for making one reproduction only. Higher density foam, used in this manner, will produce several reproductions. Such high-density, carved foam is often used to create intricately "carved" furniture reproduced in foams or polyesters by means of a room temperature vulcanized rubber (R.T.V.) mold. The parts are produced from the same low or high-density foam materials as are the plugs. Regardless of the density of foam being used the procedure is as follows:

1. Carve and shape the foam into the desired configuration.
2. Apply a release agent to this surface. (512B PVA)
3. Pour the R.T.V. over this carving.
4. Allow the R.T.V. to cure.
5. Remove the R.T.V. from the carving.
6. Apply a release agent to the R.T.V. reproduction.
7. Pour the low or high-density foam into the R.T.V. mold, reproducing the original carving.
8. Demold the carving, which will match the original carving used as a plug.

Church furniture, novelty plaques and automotive prototype units are a few additional applications for low and high-density foam products.

3. Paraffin Wax: Paraffin is generally used to produce fiberglass musical instruments such as horns or parts that will be produced only once from each mold. The process is unique since virtually any twisting curvature can be produced with this system.

After shaping the paraffin wax, apply a laminate to the exterior side of the shape. When the laminate has cured, insert a hot wire into the paraffin and the paraffin plug will melt away from the laminate. Obviously this procedure has limited uses and requires the rebuilding of a new paraffin tool after each part. However, the paraffin is reusable.