Concrete Mold Making | Page 4

Figure 20

Strips of fiberglass mat are cut to fit the latex mold and laid on top to await for the fiberglass resin. I mix 20-ounce of polyester resin and combine it with 5.5 cc's of the fiberglass hardener and mix until the mixture turns a brownish yellow.

Figure 21

The resin is poured on top of the fiberglass matting. With a squeegee the resin is forced through the matting paver the entire surface. Later I'll use the bubble roller to roll out any air bubbles that remain.

Figure 22

This is the first coat of fiberglass mat and resin, waiting to dry. The resin doesn't completely dry in this step. It remains tacky which helps in the application of the next layer of matting and resin. I'll but on three layers to give the shell mold enough strength to stand up to repeated pouring of concrete.

Figure 23

Once the fiberglass was completely dry I de-molded them using a small pry bar that I worked around the edges. The fiberglass shell, came free without difficulty because of the mold release. The photo shows both the latex mold with its brick pattern and the fiberglass shell. I will use a saber saw and trim off the four edges of each mold. These are very sharp and needle-like.