Moldmaking compound for making silicone molds

1. Clean and dry the concrete basin model(there is a circular hole at the bottom). 
2. Center the basin model on board A. Then draw a line on board A, along perimeter of the basin model. Take the basin model away and eliminate circular area of board A by using a incisive knife.
3. Put basin model on the middle position of board B. Then make a gasket circle along perimeter of basin model. Put board A down over board B.
4. Smooth the clay along perimeter of basin model to make sure that moldmaking compound will not seep.
5. Fix several nuts on four corners of board B.
6. Build mold box around basin model with screws.Then use hot glue to seal seams of mold box, which will keep moldmaking compound for making silicone molds from leaking. Spout appropriate volume of release agents on basin model and inner surface of mold box.
7. Moldmaking compound for making silicone rubber is composed of two components. Mix up these two componets. Pour the prepared moldmaking compound into mold box. You should keep in mind that the circular hole of basin model should be exactly exposed. 24hrs later, the moldmaking compound for making silicone molds will be completely cured.
8. Cover board C over the cured mold and fix it. Then turn over the whole mold box. Remove board A, board B and the clay gasket. Clean the residual clay and seal seams.
9. Spray release agent all over the surface. Then pour processed moldmaking compound into mold frame. The silicone mold will thoroughly cure after 24hrs.
10. Demold mold box and silicone molds then reassemble again. The finished silicone mold is ready for later casting.