Throw salt in a campfire and the flames flare bright yellow, which is enough to make people wonder if salt burns. It doesn't. The color is a trick of chemistry, not combustion.
Salt is not flammable. Sodium chloride is already fully oxidized, so there is nothing left for fire to react with. It won't ignite, won't burn, and doesn't decompose until about 1,470°F, when it simply melts. The yellow flare you see is the sodium in the salt emitting its signature color when heated, the same effect that makes sodium streetlights yellow.
Why Salt Doesn't Burn
Burning is a reaction between a fuel and oxygen. Wood, gasoline, and alcohol are full of carbon and hydrogen that oxygen wants to react with. Table salt is sodium that has already reacted with chlorine to form a stable crystal. Fire has nothing to offer it. Pure sodium metal, on the other hand, reacts violently with water and burns in air, which is why "sodium" and "salt" sound similar but behave nothing alike.
Why Salt Puts Out Small Fires
Because it doesn't burn, a heavy layer of salt on a small pan fire smothers it by blocking oxygen, and it absorbs some heat as it does. It won't react with hot oil the way water does, and it won't flash the way flour does. That makes it one of the two dry kitchen ingredients worth grabbing in an emergency; baking soda is the other. It takes a lot of salt, poured on rather than sprinkled, and it only works on a fire still contained in the pan. We tested it in will salt put out a fire.
Sea Salt, Kosher Salt, and Salt Substitutes
- Sea salt and kosher salt are sodium chloride with trace minerals. Same behavior: not flammable, same yellow flame.
- Salt substitutes are potassium chloride. Also not flammable; the flame color is lilac instead of yellow.
- Epsom salt is magnesium sulfate and is not flammable either.
- Rock salt for ice melt is sodium chloride, sometimes with calcium chloride, none of which burns.
Does Salt Make Fire Burn Hotter?
No. If anything, the salt absorbs a little heat as it warms and melts. The bright flare looks like more fire, but it is the same fire with a different color.
Related reading: is baking soda flammable, is sugar flammable, and how hot each flame color is.
