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Two scales that look like one

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The regulation gives three bands And our shelf gives three container ratings The numbers overlap They are not comparable So one is about the contents and one is about the wall Which produces a specific misreading A container can be well inside its rating And the reverse Which is why this property exists The definitions are about substances And nothing here says a container is suitable for a flame A candle heats its own container from the inside So read the two scales separately References

100 F and 120 F. Same units, different physics.

The regulation gives three bands

Extremely flammable at or below 20 F. Flammable above 20 and below 100. Combustible at or above 100 to and including 150.

And our shelf gives three container ratings

146 containers at -40 to 120 F, 33 at -100 to 300 F, and 29 at -100 to 190 F, published on all 208.

The numbers overlap

A 120 F container ceiling sits inside the combustible band, and a 190 F ceiling sits above all three bands. The figures look comparable.

They are not comparable

A flashpoint is the temperature at which a liquid gives off enough vapor to ignite. A container rating is what the container tolerates.

So one is about the contents and one is about the wall

Different subjects, different failure modes, and the same units of measurement.

Which produces a specific misreading

That a container rated to 120 F is somehow safe for a liquid with a 100 F flashpoint, or unsafe for one with a 150 F flashpoint. Neither follows.

A container can be well inside its rating

And its contents can be above their flashpoint, giving off ignitable vapor in a container that is not under any thermal stress at all.

And the reverse

A container can be above its rating and deforming while the contents are nowhere near a flashpoint.

Which is why this property exists

Nothing else in this library puts two unrelated measurements in the same numeric range, and this group is where somebody would conflate them.

The definitions are about substances

They are part of a labeling scheme for hazardous substances and they say nothing about containers. Nothing here says whether any product is one.

And nothing here says a container is suitable for a flame

Which is the second finding: 123 of the 208 containers are PET single wall jars and one of the four leaves is a candle.

A candle heats its own container from the inside

At the wick and along the wall above the melt pool, and 146 of the 208 containers top out at 120 F.

So read the two scales separately

Which is the whole instruction, and it is easier to state than to remember.

References

16 CFR 1500.3(c)(6): "The term extremely flammable shall apply to any substance which has a flashpoint at or below 20 degrees F (-6.7 degrees C) as determined by the test method described at Sec. 1500.43a"; "The term flammable shall apply to any substance having a flashpoint above 20 degrees F (-6.7 degrees C) and below 100 degrees F (37.8 degrees C), as determined by the method described at Sec. 1500.43a"; "The term combustible shall apply to any substance having a flashpoint at or above 100 degrees F (37.8 degrees C) to and including 150 degrees F (65.6 degrees C) as determined by the test method described at Sec. 1500.43a". These definitions describe a substance and are part of the Federal Hazardous Substances Act labeling scheme; the test method cited is not described here, and nothing on these pages says whether any product is a hazardous substance. law.cornell.edu

The Davis Pack Supply catalog, measured 19 October 2026. A temperature range is published on all 208 containers in this group and takes three values: -40 to 120 F on 146 containers, -100 to 300 F on 33, and -100 to 190 F on 29. A container temperature rating describes what the container tolerates. It is not a flashpoint, it is not a flammability statement, and it has no bearing on whether contents will ignite.

The Davis Pack Supply catalog, measured 19 October 2026. 123 of the 208 containers in this group are PET single wall jars and 146 of the 208 have a temperature ceiling of 120 F. A candle heats its own container from the inside, at the wick and along the wall above the melt pool. The 33 containers rated to 300 F and the 30 glass containers are the ones with any thermal headroom. The candles and home fragrance group is a separate group with its own shelf; this group's candle emergency leaf resolves to the store-humidity archetype instead.

Written from 16 CFR 1500.3(c)(6) and from the catalog as it stood on 19 October 2026. Those definitions describe a substance and say nothing about a container: a flashpoint is the temperature at which a liquid gives off enough vapor to ignite and a container temperature rating is what the container tolerates, so a container can be inside its rating while its contents are above their flashpoint. Nothing here says whether any product is a hazardous substance, what labeling it requires, or whether any container is suitable for a candle, a fuel or a flame. The test method cited in the definitions is not described.