Moisture contamination in urethane resin causes foaming. If it foams quite a bit, most likely the moisture is right in the Alumilite. The moisture is usually in the A-side. There is not a full-proof method of removing moisture from your system. Typically the B side will crystallize when moisture is present. The A-side, however, will not look any different. You can try to use a molecular sieve in the A-side. Mix the sieve into the resin and allow it to settle to the bottom for a couple of days. Then test the resin to see if the sieve was effective in removing the air. You can also try to vacuum the A-side to relieve it of moisture. Vacuum the A side for 20-30 minutes until it completely stops bubbling. If you don't have access to vacuuming equipment or a molecular sieve, the last chance would be to boil the moisture off. This is possible because water has a lower boiling temperature than any of the other liquids in the A-side. To boil off the material, we recommend that you put the Alumilite resin in a glass or metal container and place the material in an oven at 250°F for 2 hours. This will draw the moisture out of the system and evaporate it. If you are getting a bunch of little pinholes, the moisture is probably coming from some materials you are using (mold, cups, stir sticks, filler, etc.).