Popcorn is staining my stainless pan!

December 8, 2011 3:48 PM

Cooking popcorn with vegetable oil is discoloring my stainless steel pan. It leaves a dark yellowish stain both inside and outside around the rim. Is this a reaction with the metal? Is there a way to avoid this happening? And most importantly, is there a way to remove this discoloration? Scrubbing does nothing.
posted by stopgap to home & garden (31 answers total)

Not sure how to remove the discoloration; however, as far as preparation goes, I never use a fat to pop popcorn in a skillet or in the microwave and it turns out just fine.
posted by HotPatatta at 3:53 PM on December 8, 2011

Sounds like a reaction to the heat. How are you scrubbing? Barkeeper's Friend and a copper scouring pad always gets my clad pans looking new, no matter how discolored.
posted by supercres at 3:57 PM on December 8, 2011 [4 favorites]

I'd try scrubbing it the a slurry (paste consistency) of baking soda and water. I don't know how to prevent that from happening.
posted by purple_bird at 3:58 PM on December 8, 2011 [2 favorites]

I find scrubbing my stainless steel pan with a slurry made from Barkeeper's Friend and water works quite well.
posted by grouse at 4:03 PM on December 8, 2011

I'm 90% sure what you're describing has nothing to do with the popcorn, and is actually discoloration because the pan is getting hot with (effectively) nothing in it and oxidizing.

I'm 99% sure it won't hurt you.

If you'd like to get rid of it, you can try boiling coke (the soda) in it. Just make sure you stop it once it hits a boil (then take it out and scrub it) and don't let it actually boil in there. (When coke boils it creates acrid smoke that is basically eye poison. Don't ask me how I found this out. Ow.) But coke oughta help. It definitely does an awesome job of removing other weird/burned/stuck on pan stains.
posted by phunniemee at 4:03 PM on December 8, 2011

I have a whirly pop that is completely stained like this. I've had a couple of these and have managed to keep them clean for awhile but it seems like there must be some kind of reaction with the metal so if you make a lot of popcorn like I do you might as well have something devoted solely to popcorn. The whirly pop also doubles as a conversation piece...
posted by fromageball at 4:05 PM on December 8, 2011

Yeah, I'm 99% certain it's popcorn-related because this pot has been pristine for about 8 years and the staining coincided with the start of popcorn making about 3 weeks ago. This is cooking with the lid on, but strangely the worst staining is on the outside of the pan. It almost looks like the pattern of a dripping liquid.

I'm not against having a popcorn-devoted pan, but I don't have much extra storage space.
posted by stopgap at 4:09 PM on December 8, 2011

I think it's from the oil and that you can avoid it by using a little bit (really, just a little bit) more oil and a little bit less heat. I think what you want is for the popcorn to pop because of accumulated steam, not really heat, and if you go more slowly that can happen without that rock hard film you're describing, which I think is basically burnt oil.
posted by A Terrible Llama at 4:12 PM on December 8, 2011 [1 favorite]

If the stain is oil based and not discolouration due to excessive heat then you might want to try oven cleaner. If you can find lye (sodium hydroxide) it's basically the same thing and often cheaper.

If you want to avoid chemicals then I've taken out many a tough stain with the stainless steel chore boy.
posted by talkingmuffin at 4:14 PM on December 8, 2011

I had the same thing with my tri-ply stainless calphalon popcorn pan (we liked to use a small flat-bottom wok!). I think it's just a little bit of polymerized fat haze but BKF cuts through it and it's pretty easy as long as you keep after it.
posted by ftm at 4:16 PM on December 8, 2011 [1 favorite]

This is most likely polymerized oil. Should be easy to scrub off with steel wool or something else sufficiently abrasive. A wire brush in a drill should do nicely (only partially joking - I removed a lot of crap from the bottoms of some aluminum pans with a wire brush).
posted by pombe at 4:19 PM on December 8, 2011 [3 favorites]

Like Pombe suggests, this is polymerized oil. Ammonia-based cleaners (like oven cleaner) will soften it and make it easy to remove.
posted by jon1270 at 4:31 PM on December 8, 2011

The advantage of baking soda or bkf is that they don't or minmally damage the finish on the surface, unlike metal wool or brushes.
posted by a robot made out of meat at 4:32 PM on December 8, 2011 [2 favorites]

Try cooking rhubarb in it.
posted by kjs4 at 4:49 PM on December 8, 2011 [1 favorite]

Polymerized oxidized oil. Oven cleaner to remove.

This is the same varnish that people intentionally build up on cast iron pans. It makes the pan nonstick, but is unsightly on stainless. Ovencleaner and a half hour soak will remove it.
posted by bonehead at 4:52 PM on December 8, 2011

Yep. The oil evaporates, hits the lid and drips down the sides. Scrape it off with a plastic knife and clean up the rest with bar keepers friend. I like to use the blue non scratch Scotch-Brite pads. DO NOT use the green ones, they will scratch. Regular SOS pads should also work. (Stainless is harder than the mild steel it is made of = no scratching.)
posted by gjc at 4:56 PM on December 8, 2011

To avoid it in the future, avoid keeping hot oil in the pan for long periods. The coating isn't dangerous nor will it affect the pan's cooking performance. It is easily removed by oven cleaner with damaging or scratching the pan, if that is what you wish.
posted by bonehead at 4:57 PM on December 8, 2011

How long do you let the pan sit before you clean it? I've had the same exact problem when making popcorn with vegetable oil, and I've found that it mostly happens when I let the pot sit for more than a few hours without cleaning it. When I'm feeling extra lazy I'll fill the pot with water immediately after I pour the popcorn out of it; this seems to buy me some extra time before I actually have to clean it (and it makes a very satisfying hissing noise).
posted by enlarged to show texture at 5:01 PM on December 8, 2011

(Oh, and like everyone else is saying, Bar Keeper's Friend works like a charm.)
posted by enlarged to show texture at 5:02 PM on December 8, 2011

Try 600 grit wet sandpaper. I keep a little piece ( 3" x 3") of it near the sink for just this situation. Use it wet.

Works wonders on white Corelle, copper, stainless steel. You can even polish Petosky stones and other soft minerals with it.

You only need a little piece, so when you buy some and see how wonderful it works, you can gift small pieces to your friends and they will think you are a wonderful person.
posted by bricksNmortar at 5:05 PM on December 8, 2011 [1 favorite]

Ammonia* and/or Dawn dish deterg. will clean baked-on(polymerized) oil. Try soaking it with ammonia; if you can scrape it off with a spoon, it's the oil. Even if the heat is changing the color of the pot, it's not harming it. Shiny cookware is nice, but well-used cookware promises a good meal, in my experience. If your pots are laminated, i.e., RevereWare has a copper bottom laminated to stainless steel, then very high heat can make it separate. I've abused my Revere pots and they're fine.
* never mix ammonia and bleach; it's very toxic.
posted by theora55 at 6:09 PM on December 8, 2011

This is why you need a dedicated popcorn pan. Old pressure cookers without the gasket work great and are dirt cheap at the thrift store. Why bother scrubbing so hard if you're just goin to make popcorn in it again? Get a cheap pan and throw it out when you can't stand the sight of it anymore. Rinse, repeat, enjoy delicious popcorn.
posted by cosmicbandito at 7:53 PM on December 8, 2011

I think it's possible that the act of heating this pan for 15 minutes on medium high is melting some of the 8 years of "usage" stuck under the rolled lip. I know we all like to think we wash our dishes to a pristine state, but unless this pan was sitting unused I think it's just gunk. On the inside, I've noticed that I'll get a yellow oil residue if I heat the pan too long with only oil, like it evaporated or reduced. Steel wool or a scrubber takes care of it.
posted by rhizome at 8:17 PM on December 8, 2011

kjs4's rhubarb suggestion works because rhubarb has lots of oxalic acid. So does a cleanser-like product called "Barkeeper's Friend", which I find invaluable for keeping stainless steel bright and shiny.
posted by straw at 8:27 PM on December 8, 2011

If you switch to using a cast iron pot to pop your corn in, then what you're now seeing as a stain would just become seasoning.
posted by flabdablet at 2:59 AM on December 9, 2011

You are overheating the oil. Turn down the flame a little bit. I know this a a tough compromise with popcorn. You might also try some different oils. Peanut oil is very good with high heat.

There were good suggestions for removing it, blue (not green) scrubbies, barkeepers friend, etc. I also like dishwasher detergent soaking. It is much stronger than the stuff made for washing in the sink and that might come into contact with your skin.
posted by caddis at 7:24 AM on December 9, 2011

I get a sticky brownish film on the inside of my stainless pots when I cook popcorn in them (yes, I probably have a tendency to overheat the oil). The best way I know of to get rid of it is to boil a bunch of baking soda and water in the pot (lots of baking soda), leave it until it it's cool enough to handle, and then scrub with a brush or scrub pad.

This restore the pan to a nearly pristine condition.
posted by mskyle at 7:58 AM on December 9, 2011

I use Dawn Power Dissolver to solve this exact problem. Works a treat.
posted by trip and a half at 11:31 AM on December 9, 2011

By the way, polymerized cooking oil is chemically fairly similar to oil-based paint. So you might get good results from paint stripper.
posted by flabdablet at 6:28 PM on December 9, 2011

Some great advice here as usual. Using a baking soda paste and a plastic scrubber I was able to remove all the oil from the outside of the pan with a bit of effort. I will use a cheap pan for popcorn in the future with the expectation that it will get kind of gross.

I also have to note that I doubt the heat level has much to do with the discoloration. Just because the popcorn is popped on the stove doesn't mean it takes any longer than a microwave. 15 minutes!? I'd estimate the whole cooking process takes about 3 minutes on medium heat from cold pan to popped and ready to butter.
posted by stopgap at 8:03 PM on December 12, 2011 [1 favorite]

It takes kind of a long time for me to pop popcorn, for what it's worth. I'd be feeling mighty speedy about three minutes. I do medium-low in a fairly heavy pan. I've never timed it, but I think ten or fifteen minutes might be about right.*At any rate, I think one thing you might watch out for is if the flames fan out toward the edge of the pan, heating the sides as much as the bottom.

*I like to melt garlic in a separate pan with some slivers of garlic
posted by A Terrible Llama at 1:42 AM on December 13, 2011