The golden rule is: The thicker a candle and/or the more colour it contains, the thicker its wick must be. Paraffin-, beeswax and stearin candles all require different wicks. We provide information about wick thickness along with the various types of wick. These wick sizes are based on uncoloured candles, since wick thickness also depends on the colour of the wax, and even on personal preferences. Light a sample of a new range before you produce a batch for sale. Your test is definitive. If the wick is too thin, the candle will leak. If it's too thick, the candle will create smoke.