I learnt a lot about mold making while I was in Jingdezhen. I have always been very curious about how molds used in mass productions are made. I was told the mold maker would make a mother mold of the prototype and then make a case mold of the mother mold so they can just keep duplicating the mother mold. The case mold can be made from plaster silicone or rubber depends on how much their client are willing to pay.
I have a mold of chain links which I want to duplicate so I can cast tons of chain links at the same time. I decided to make a rubber case mold of the chain mold.
Step 1. Make a copy of your original mold
Because you need to use clear shellac to seal the mold so it is poreless. But that means that mold is useless after you are done with it. Always have a back up in case something goes wrong.
Step 2. Seal your plaster mother mold with clear shellac.
You can get a clear shellac spray or the brush on ones. I added food dye in the brush on shellac so I can tell how many coats I put on.
Step 3. Chose the right product for your purpose
I went to Reynolds Advance Materials. They have a lot of good products. I bought the gallon unit of ReoFlex 30. https://www.reynoldsam.com/product/reoflex-series/
Step 4. Set up for the rubber pour.
Make sure you do it on a very level and smooth surface. And set the cottles for your mold and if there are any gaps underneath the mold, fill it with Plasteline.
Step 5. Follow the instruction and pour mix on your mold
Step 6. Let it cure overnight(each product have different cure time, follow the instructions)
Step 7. Wola. Now you have a mold baby making factory:)
Step 8. Now you can just keep mix and pour plaster into the rubber case mold and pop them out like ice cubes.