I made some candles in 8 oz. tins using pre-tabbed 2/0 wicks.

The first problem was that no matter how slow I cooled them, they cracked down the middle. I got around this by doing a second pour and filling in the crack. Is there a way to avoid the crack in the first place?

Second problem was that when burned, they burned a ping pong ball sized hole straight down leaving about an inch of wax around the sides. Do I need a different wick?

Any advice will be appreciated.