Degassing resin is trickier than it sounds. The resin container should only be about third full to allow bubbles to expand and burst. There is usually quite a bit of foaming. Volatile material in the resin can help remove air bubbles much faster. Most resin contains enough residual volatiles that adding some is not necessary. But, if you find that after pulling vacuum for a long time you have a foam that won't go away, and when you release the vacuum the foam shrinks but is still on the surface then you have a problem with stable air bubbles that won't pop.
A few drops of acetone or other solvent will flush all air out of the resin very rapidly under vacuum. When vacuum is released all bubbles will be completely gone because any residual bubbles are acetone vapor bubbles which will condense and go into solution.
Gentlemen,
I seem to recall that the addition of carbon dioxide as the vacuum is released would encourage any residual bubbles to burst. Does this have any basis in fact or is it an urban myth?
B.E.
I can't think of any benefit that carbon dioxide would provide toward eliminating bubbles at that point. If the resin is mixed under CO2 then the bubbles would be CO2 and perhaps these might dissolve more readily than air bubbles.
I have never added gas. Putting a 1/3 full container in a vacuum chanber and applying vac for five minutes almost always does the trick. As well, if this is a clear casting system, it should relieve air on its own or with some vibrations, ie rubber mallet smacks on the mold.
Reveiw you rprocess as well, I have found many times that more air is added in application and vac of the system is not as productive.
