is it just sad?
July 20, 2009 9:36 AM   Subscribe

2-Part question: 1) Why did my wok catch fire? 2) Why did it turn blue?

I was cooking fish last night using a stainless steel wok.

it was on the eye of the stove heating up, and i let it stay for a little while longer than i had planned, because i was occupied preparing the stuff to go in the wok.

i finished prep, and poured less than a tablespoon of canola oil into it, which immediately started to boil. i turned around, and then looked back, and the oil had caught fire, with a bright orange flame about 2 feet tall (way cool!!!).

after i put it out, i poured a bit of water into it to cool it off (free wok, so i didn't really care about ruining it, just wanted to get it off the stove), and let it cool for a while.

i looked at it this morning, and the whole bottom of the wok is blue (also, way cool!!!).

why did all this happen? i thought the smoke point of canola oil is much hotter than my electric stove could bring anything.
posted by chicago2penn to Food & Drink (8 answers total) 1 user marked this as a favorite
All steel turns blue when heated enough. Sometimes you get a nifty rainbow effect of rippling bronze and blue colors, it looks like an oil slick. This is what "blue steel" means, though that's usually referring swords or guns, rather than woks.

You can scrub it off.
posted by rokusan at 9:49 AM on July 20, 2009

I hate this keyboard.
posted by rokusan at 9:49 AM on July 20, 2009

Compared to a cast-iron frying pan, or even an aluminum frying pan, a wok doesn't have much thermal mass. If you try to heat it up without any food in it, and set your electric stove to the power level you'd use if the wok was full of food, then the empty wok will heat up a lot more than you expect. That's what happened to you.

Sadly, woks don't really work very well with electric stoves.
posted by Chocolate Pickle at 10:08 AM on July 20, 2009

The wok was hot enough that your oil immediately hit the flash point / fire point. If you see oil "boiling", that's your "uh-oh" moment. If it's boiling then something is vaporizing, and in this case that something is highly flammable*. So don't say "cool!" and go in for a closer look at that point.

(* that's "inflammable" for you picky folks)
posted by madmethods at 10:21 AM on July 20, 2009 [1 favorite]

For future reference:

When heated properly, cooking oil shimmers (you'll know it when you see it.)

If it is smoking or doing something else like boiling, it's too hot.
posted by 517 at 10:25 AM on July 20, 2009

The color is from an oxide that forms on the surface of the steel as it heats up. There's a chart on this page.
posted by Rhomboid at 11:33 AM on July 20, 2009

You've blued your steel wok. Gun owners use acid treatments to achieve the same effect, because it wards off rust.

(Technically, the bluing is a form of iron oxide, but it is (1) stable and (2) not hydroscopic/water-loving, so it forms a protective coating against ordinary , orange-flaking, iron-eating Fe2O3 rust.)

This is fairly desirable. The next step is to oil it before storing, and heat it nearly to, or just to, the smoke point before adding anything, in order to blacken the surface with a film of carbon.
posted by IAmBroom at 12:10 PM on July 20, 2009 [2 favorites]

Your wok is not sad, it is totally happy to have been involved with an awesome kitchen accident like shooting flames. If only all of your cooking equipment should be so lucky. When stir frying, prep everything first. That wok is gonna get hot fast and it take flippin' for-evar to cut everything up. Unless you totally like the shooting flames, then just do it outside and shave your head first. I heat until I see a whiff of smoke then the food hits the oil
posted by Foam Pants at 2:08 PM on July 20, 2009

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