Why you cannot skip it

Every other decision in this craft is a guess until a candle has been burned all the way down.

A candle is a system

Wax, fragrance load, dye, wick and vessel behave as one object. Change any of the five and the others behave differently.

A fragrance oil at 8 percent burns differently from the same oil at 10. A dye adds solids the wick has to pull through. A vessel one centimeter wider needs a larger wick, and a larger wick in a narrower vessel overheats the glass.

Which is why a wick chart is a starting point and never an answer. The chart does not know your fragrance, your dye or your jar.

What the standard actually asks

ASTM F2417 sets minimum fire safety requirements for candles: flame height, stability, secondary ignition, and behavior at end of useful life.

Those are not properties you can calculate. They are observations of a candle burning, in the vessel it will be sold in, with the wick it will be sold with.

The standard is voluntary. What it describes is the ordinary meaning of a candle being safe, and there is no other route to knowing it.

What testing is evidence of

Retailers ask whether you test. Insurers ask. And if a candle you made ever causes harm, the question will be what you did to establish it was safe before you sold it.

A dated burn record, per formula and per vessel, is the answer to all three. An untested candle has no answer at all, and "I followed the wick chart" is not one.

The cost of not doing it

A burn test costs one candle and several hours of attention spread over a few days.

Not doing it costs a product that tunnels and disappoints, or a vessel that cracks, or a flame that does something a customer did not expect on a shelf they were not watching.

It is the cheapest insurance in this craft and the step most often skipped, because the candle looks finished the moment it sets.

References