Sizing a wick

A consequential decision in the craft, and the one no supplier chart can make for you.

The chart is a starting point

Suppliers publish a wick size against a vessel diameter. Use it to pick the first candidate and the one either side of it.

Then test all three. That is the method, and it is three candles per fragrance per vessel.

What the chart does not know

Your fragrance, which is fuel and changes the burn.

Your load, which changes it again.

Your dye, which adds solids.

Your wax's exact formulation.

The wall thickness and shape of your vessel, which decides how much heat comes back into the pool.

Five unknowns, which is why a chart can only narrow the field.

Working through it

Pour three identical candles with three adjacent wick sizes, cure them the same length of time, and burn them in four-hour cycles side by side.

Side by side matters. Differences that are invisible in a single candle are obvious between two, and the middle one is often the answer.

Judge on the full burn, not the first cycle. The bottom of the vessel is where an over-large wick becomes a problem.

Two wicks

Above about 8 cm of diameter a single wick usually cannot reach the wall without running far too hot, and the answer is two wicks, each smaller than the single one would have been.

Placement is then its own variable: too close together and the flames merge into one hot column, too far apart and the middle never fully melts.

A multi-wick candle is a harder test and it is the point at which a wide vessel stops being a simple upsell.

References