A great many friends have asked me to share the secret of making scented candles at home, though I tell them repeatedly that there is no great secret. Any online guide will teach you the basics, and once you have those the rest is imagination.
What you need
Wax. Soy is the usual choice for beginners: it melts at a low temperature, holds scent well and cleans up with soap and water. Paraffin gives a stronger scent throw; beeswax smells lovely on its own and takes added scent poorly.
Wicks, sized to the diameter of your container. This is the decision people get wrong most often, and it matters more than anything else.
Fragrance oil made for candles. Not essential oils, in most cases – many simply burn off or will not bind with the wax.
Containers, heatproof. Jars, tins, teacups.
A thermometer. Not optional if you want consistent results.
A double boiler, or a heatproof jug in a pan of water.
The process
Melt the wax gently to the temperature its instructions specify. Do not rush this with direct heat – wax is flammable and overheating it is the main hazard in the whole process.
Add the fragrance at the temperature the oil specifies, usually a little below the melting point, and stir thoroughly for a couple of minutes. Under-stirring is why some candles smell strong at the top and of nothing further down.
Secure the wick centrally, pour slowly, and leave it alone.
Wick size, since it matters most
Too small and the candle tunnels – it burns a narrow well down the middle and leaves a ring of wax untouched, wasting most of it.
Too large and it burns hot, smokes, and can crack the container.
Wick manufacturers publish sizing charts against container diameter. Use them, and test one candle before making a batch.
Cooling
Slowly, at room temperature, away from draughts. Cooling too fast causes cracks and a lumpy surface.
Let the candles cure before burning – a few days for most waxes, up to two weeks for soy. The scent develops considerably during that time, and a candle burned the same evening will smell far weaker than it eventually would.
The first burn
Tell anyone you give a candle to: the first burn should last until the melted pool reaches the edges of the container, usually two to three hours.
Wax has a memory. If the first burn only melts a small circle, the candle will tunnel down that circle for the rest of its life.
Safety
Never leave melting wax unattended. Keep a lid nearby to smother a fire rather than water, which will spread it.
