While trying these tips may not solve the problem, they rule out common mistakes before deciding to test a different size wick.
If flame is too small, leave the wick longer before lighting (about 5/8" or 16 mm). If the wick is trimmed too short, it won't create the correct flame height and enough heat to melt the wax. The flame should be approximately 1" (2.5 cm) tall.
If flame is too tall and/or flickering, trim the wick shorter before lighting.
If the melt pool doesn't go to the edge of the container, (1) allow the candle to burn for 3-4 hrs. at one lighting. Burning the candle for a shorter period might not allow time for the wax to melt. (2) Be sure you have a 1" (2.5 cm) flame.
If there's wax left on the sides of the jar after the first one or two burn cycles, continue the burn test if it's 1/8" (3 mm) thick or less. During the first cycles, most of the heat from the flame goes out the top of the candle and may not create an ideal melt pool. As the wax is consumed and the flame gets down inside the container, more heat is retained inside the jar and may melt off the wax left from the first cycles.
If the wick is sooting, there are three factors that could cause this:
- Poor quality wax
- Poor quality or too much fragrance oil
- Wrong size or type of wick
Sooting is a result of too much fuel (wax plus fragrance plus dye) being pulled up through the wick to burn off cleanly at the flame.