Sometimes, a candle will just refuse to leave the mold that gave it shape. And when it happens, it can very quickly get on your nerves and make you want to throw it all through the window...
This happens frequently with candles made totally or partially of beeswax, because beeswax is sticky and does not shrink as it cools off like paraffin wax does. To avoid this problem, there are some precautions you can take.
Before you start pouring beeswax into your metal or polycarbonate mold, spray a thin layer of mold release spray inside the mold. One spray normally helps release about five candles. Once completely cooled off, your beeswax candle should pop out of the mold without any problem.
As far as candles made of paraffin wax (especially if you've added stearic acid) or soywax (the pillar blend) are concerned, you normally don't need to use mold release spray: the natural shrinkage of these waxes as they cool down is sufficient to make the unmolding process an easy one. Nonetheless, if one of your candles refuses to come out of the mold, first make sure it had time to cool off completely (allow at least six hours at room temperature); if that's the case, place the mold in the fridge for fifteen minutes and try again (do not put it in the freezer to speed things up, you risk cracking the surface of your candle). Repeat in cycles of fifteen minutes if the candle still won't come out of the mold.
The "real" candlemaking mold release spray can be tricky to find, depending on where you live. If needed, you can replace it with a silicone spray (right on the picture) or a baking spray (left).