When to change the wick

Wick sizing is the main adjustment in this craft and it is made one step at a time, with a full test between steps.

The two directions

Under-wicked: no full melt pool at four hours, tunneling, a low guttering flame, weak scent throw.

Over-wicked: melt pool too deep, flame too tall, soot, mushrooming, a vessel too hot to hold, a candle that burns down far too fast.

Both are visible in the first test cycle. Neither improves on its own.

Going up

One size at a time within the same series.

Re-run the full test, all the way down. A wick that fixes the melt pool at the top can be dangerous at the bottom, where the flame is closer to the base and the glass is already hot.

If going up fixes the pool and introduces soot, the answer is a different wick series rather than a different size.

Going down

Same discipline. Down one size, full test.

Going down will usually reduce the scent throw as well, because throw follows the melt pool. That is a trade between a quieter candle and a cleaner one, and clean wins.

One change at a time

The failure in this craft is changing the wick and the fragrance load together, getting a better candle, and not knowing which change did it.

Number every test candle, change one variable, record the result. Four tests done properly beat twenty done in parallel, because only the four tell you anything you can reuse on the next fragrance.

References