Mold release- When is it used ?

If you casting resin in a silicone mold (Amazing Mold, Plat series, HS series, etc) then no need for a release. Once you've cast enough and the mold itself feels a little "dry" then rub it with a little oil - either silicone oil or even a little tiny bit of clean cooking oil.

If you're just using one piece molds, you won't need to use the rubber to rubber mold release as it's used for two piece molds. It goes in between the two layers of silicone so that they don't bond and you can't remove the casting you're making from them.