Frank, can you agitate the bubbles out in the pot ? I've found that there where some batches of Calhoun that did bubble in the microwave a little, but they dissipated when I had the plastic in the hot pot being stirred for 10 -15 min.
I'm wondering if I bringing the LW plastisol to a gel state and then putting it in the hot pot will help the bubbling issue. For tube dipping, this is the only way I can think to resolve the issue.