How to Avoid the Draft
The most well-made candle with the perfect combination of wax and wick will burn poorly and drip if it is subjected to a draft. What a draft does is to create more oxygen on one side of the flame than on the other, causing uneven burning. If your candle is not burning properly, check the air flow and move it to a draft-free location.
Another form of draft is oxygen deprivation — this occurs when a container or large pillar candle has burned down sufficiently so that the hole made by the melted wax's consumption in the flame is so deep that not enough oxygen can get in to feed the fire. This is a common and regular problem with pillar and container candles.
To correct oxygen deprivation in large candles, use paraffin instead of wax or a mixture that produces a soft wax with a lower melting point. Don't burn the candle longer than three hours per session so that the pool of wax can resolidify in between use.