How do you make candles that don't produce black smoke? A candle smokes when the wick's too large. The candle provides insufficient fuel to the too-thick string, and gives off unsightly columns of bitter-smelling smoke, while burning. Choose the correctly sized, no smoke candle wicks, corresponding to the width of your candles, to best prevent these errors.

Reputable candle making suppliers should provide you with the correctly named and labelled strings, e.g. 1" (2,54cm), or 2" (5,08cm) wicks, match candles with 1" and 2" diameters respectively.

What if labelled candle making thread's not available? Buy short lengths of different size wicks, and do the following: make a wide candle with each thickness, (so it burns down the middle). The candle doesn't have to be particularly tall. Burn it for several hours; extinguish it; measure the width of the burnt-out hole, and label the wick. This takes time and patience, but keeps the guesswork out of your future candle making efforts.

During the testing process, too-small cotton cores might drown in the liquid wax. That's OK. By this stage, pronounced pools will have formed, with measurable diameters.