I made some plaster molds. I need help cause the baits get a white color from the plaster. I also got some molds I bought, made of plaster, and they are fine. It looks like something has been put on these molds to stop this from happening. It's like a coat of yellowish something. Does anyone know what i'm saying?
Try some good old elmers white glue like the kids use in school. After the plaster goes through it's own heating process and starts to cool then it is the time to remove the originals and clean up the mold with a knife. Then put it in the over at 325 for at least an hour to remove the moisture. The glue wont stick well with moisture still in the mold.
Get a small cup or shot glass because it is time to flood the mold. 1 part water and 3 parts glue to a milky consistency. Then spread the glue over all mold surfaces to seal. Let it remain in the cavities for a couple of minutes, swish it back and forth to ensure good coverage. Drain excess by shaking the mold and after the glue dries it's ready for a test pour. Sometimes a second coat is needed. If you have bubbles in your pours you can apply more glue in only those cavities by flooding or with an artists brush.
It can take the heat somehow. I use a brush that Harbor Freight sells in a pack to paint the whole surface of the mold to make it look better and easy to clean up. I got the POP at walmart in the hobby section. They had #3 and #5 boxes and I found sculpy right next to it.