Originally Posted by Beer980
Flood the cavities with a mix of water and elmer's white glue...start with 1 part water and 3 parts glue...milky consistency...spread the glue over all mold surfaces to seal with a small paintbrush...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...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. You can also fill in imperfections with the glue wash.
Yup, what he said. I use Elmer's Glue-All.