I made a few gel candles, one in a cylinder and a couple in wine glasses, and after a few days, I had these big flat bubbles around the sides about 1/4"-1/2" or so. Any idea why? It doesn't seem to happen in, say, a normal shaped candle jar, so I'm thinking it's the shape of the container but I can't see why it would even happen. Does gel shrink maybe? I used a heat gun on one and put one in the oven and they haven't come back, but I'm wondering now if I have to always do that.
Thank you for any replies!