When to stop burning your candle:
If you have ever read the warning label on the bottom of a candle you'll know that you're supposed to stop burning your candle when you get to 1/2 inch of wax on the bottom. This is to keep you safe. If you burn your wax too low the flame could potentially heat up the bottom of your jar so much that it could crack or shatter.
Don't worry though, the wax at the bottom is NOT wasted. Just freeze your candle, pop out the wax and throw it in a wax warmer. Let us know if you have any questions!