One trick I’ve used with molds is to “grease” them with a small amount of soap batter using a gloved hand prior to pouring the batter into the mold. It forms a much cleaner seal without the air bubbles. Has anyone else tried this?
Thanks! I'll give this a shot next time. I believe the bubbles in this case were amplified by some clumsy stick blending combined with waiting too long after I hit thin trace. I should have poured as soon as I hit it... Argh. I'll try your suggestion on my next attempt.