The silicone trimmed-off.

 

 

 

 

The first half mold finished. Plaster mother mold and silicone mold together.

 

 

 

Next half begins. Again, apply a clay blanket 1/4 to 3/8 inch thick to exposed object and mold. Remember, the clay will eventually become the shape of the poured silicone later. I carved some half-round indents onto the plaster in each corner to create an interlock with the 2nd half.

The two molds ready for the 2nd half plaster mother mold to happen.

 

 

 

Ready for plaster to be poured; each mold boxed, with a pour sprue for the silicone. Seal edges of mold along the sides of the box to prevent leakage. Apply spray-on mold release liberally everywhere.

 

Marks on the tube show how deep to pour the plaster. One inch is enough. Light weight is better.

 

 

 

Poured OK. Allow to dry at least 48 hours. Plaster continues to harden for days.

 

 

 

Remove the box and tube, open the mold carefully using fine wooden wedges. Don’t force it.

 

 

 

Remove the clay blanket, you’re done with it. Wax the whole surface of the plaster with Briwax, and spray release on it and the first side, and model, &c.

 

 

Reassemble the molds, ready for casting the silicone. Seal the funnel sprue area with clay.

 

 

 

The silicone poured. See the clay seals around the sprue required to keep the silicone in the mold.

 

 

 

Cure silicone 24-48 hours, and open the plaster mold. Trim off any over bleed.

 

 

 

Open the silicone mold.

 

 

 

 

Remove the model. Nice. This is what it’s all been for.

 

 

 

 

Reassembled molds, ready to be poured with wax, plastic, or cement.

 

 

 

This whole 2nd half mold was another 6 sessions of work, about 4-6 hours each, or about three weeks of weekends and nights after work. My October, Happy. These are two good molds and now I hope to get some good product out of them.