Tunnelling occurs when the flame of an underwicked candle isn’t strong enough to give a full melt pool (FMP) and a “tunnel” develops down the middle of the candle, leaving a residual coating of wax on the inner wall of the candle. Severe hang-up and mild tunnelling are effectively the same thing.

Temperature control

One way to avoid hang up is to keep a warm ambient temperature in the room where you burn your candle. As a general rule of thumb, we would recommend a temperature of 18°C to 25°C.

Change the wick

Hang up can usually be avoided by choosing a suitable wick for your candle, so it’s always worth experimenting with different wick families and sizes. The basic procedure is to increase the wick size until hang up doesn’t occur. However, be careful not to pick a wick that is too big as this will increase the risk of sooting, so finding the right balance between hang up and sooting is the key.

Add paraffin

Hang-up is more common with plant-based waxes than with paraffin waxes, as paraffin waxes are more ‘cohesive’ due to their long-chain hydrocarbon molecules. This means paraffin waxes tend to stick together, whereas plant waxes can break apart, leaving residue on glassware. So, adding paraffin wax, will result in a more ‘cohesive’ blend that is less likely to leave residue on the glass or hang up.