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Aluminum Pans

I've noticed that whenever I put my aluminum cake pan and baking sheet in the dishwasher, it gets a chalky, grey residue that comes off on your hands. It concerns me that this isn't safe (I scrub it off by hand before using). Does anyone know what this film is, and why a dishwasher brings it out?

Amanda is a co-founder of Food52.

asked over 4 years ago
17 answers 13574 views
516f887e 3787 460a bf21 d20ef4195109  bigpan
added over 4 years ago

I've not experienced this, but wonder if it is caused by the detergent you use. Powder or liquid? Maybe try a different brand to see what happens.

67544da8 1862 4539 8ec8 2d9dfc2601bb  dsc 0122.nef 1
added over 4 years ago

I found this explanation via google..http://chowhound.chow.com...

23b88974 7a89 4ef5 a567 d442bb75da04  avatar
added over 4 years ago

Very interesting and lengthy discussion. Bottom line for me is don't put your aluminum pans in the dishwasher.

23b88974 7a89 4ef5 a567 d442bb75da04  avatar
added over 4 years ago

I've had this happen as well. Asked friend/chemist, and the conclusion was that the gray film is something called atomic hydrogen. It is basically the dishwashing soap interacting with the aluminum, that causes the metal to flake. Also, the high heat of the dishwasher accelerates the reaction.

Basically, I was told to hand wash aluminum items...

Hope this helps.

2b00435b fe24 44bb afe2 ad3364f28f79  1390710 10151917400148928 1193325941 n 1
added over 4 years ago

That sounds like soap scum to me. But as others, above have said, Its probably not good for you. In general, I avoid aluminum as a cooking material. Its reactive, and the thought of eating metal (even at the atomic level), does not appeal to me.

Dcca139f 78d5 41a3 b57b 6d6c96424a1c  img 7818
added over 4 years ago

I agree with Darlene -- you're best off hand washing your aluminum. In general, the chemicals in automatic dishwasher detergents are reacting with the aluminum, resulting in discoloration and the grey residue you're seeing. In the last few years, many companies have reformulated their detergents (for example, due to many states banning the use of phosphates in dishwasher detergents) and are continuing to tweak them, so that's why you may be experiencing this for the first time, regardless of whether you've switched brands.

C8ffa92e 3766 46b4 8290 dbef5c382a03  james joyce 1
pierino

pierino is a trusted source on General Cooking and Tough Love.

added over 4 years ago

I never, ever put my serious pans in the dishwasher, aluminum or not. Same deal with knives.

84baef1b 1614 4c3d a895 e859c9d40bd1  chris in oslo
Greenstuff

Chris is a trusted source on General Cooking

added over 4 years ago

EmilyC has the story. This started to happen when the formulations of dishwasher detergents were changed to remove phosphates. The changes and its effect on aluminum were not publicized, but here's one NYT article:http://www.nytimes.com... . I have a few cheap knives with aluminum handles that I routinely put in the dishwasher, and they suddenly turned black. They are the only aluminum I continue to wash in the dishwasher.

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Sam1148

Sam is a trusted home cook.

added over 4 years ago

It may be time to clean your dishwasher. Some materials hold on to soaps that tend to hang around in the dishwasher. Especially if you have hard water. You'd be surprised how much soap that hangs about in the dishwasher. (I've taken my apart before--surprise!)

To clean it run it on a short wash cycle empty and add a few cups of white vinegar. That will dissolve most soap residue. Rinse, and repeat, rinse again with out the vinegar.

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Amanda Hesser

Amanda is a co-founder of Food52.

added over 4 years ago

Thanks for this tip -- going to do it this weekend.

23b88974 7a89 4ef5 a567 d442bb75da04  avatar
added over 4 years ago

Yes, there is a chemical reaction that happens that blackens or greys the aluminum pans. I had this happening even with phosphates in the dish detergent, so it's not that.

Note this will also happen if you use certain cleaners on brushed aluminum fixtures - our light fixtures and some window trim were ruined this way - they are completely grey and smudged looking and there is no way to repair it. I believe it is products that contain ammonia, like windex, but I'm not sure. Someone else was cleaning for me for a few months, and I'm not totally sure what was used.

7b500f1f 3219 4d49 8161 e2fc340b2798  flower bee
added over 4 years ago

I have a small knife that belonged to my grandma. It's simple and appeared to be made of one kind of metal, but somebody made the mistake (unknowingly) to put it in the dishwasher. The handle of it, made of aluminum, deteriorated very rapidly and turned from somewhat shiny to very dull and powdery, as if acid damaged surface. I asked my uncle about it because metals are his area of exeprtise and he took it with him to give the handle some kind of a bath in order to prevent future deterioration. So I believe the reaction is indeed unsafe because it indicates a bare aluminum surface.

84baef1b 1614 4c3d a895 e859c9d40bd1  chris in oslo
Greenstuff

Chris is a trusted source on General Cooking

added over 4 years ago

Here's what NPR had to say about it http://www.npr.org/2010...

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added over 4 years ago

That's why I don't put my aluminum pans in the dishwasher - always hand wash...

33f00148 b116 47f0 8789 76ae3bdb2bbb  photo 1
added over 4 years ago

I find that I only get that layer on the bottoms of my pans. I thought maybe it was somehow related to contact with the gas flames, but this sounds like a much more plausible explanation. I think I will also start handwashing....

8a5161fb 3215 4036 ad80 9f60a53189da  buddhacat
SKK
added over 4 years ago

Residue not healthy and what takes it off is soaking in vinegar of lemon juice.

0f493ab9 068f 4498 ba2c 95c992214d52  sit2
Sam1148

Sam is a trusted home cook.

added over 4 years ago

I think the chalky powder mentioned is in fact soap residue, as the Aluminum reaction described is more of a dark stain.
I get that powder stuff every few months and then clean the machine while empty with the vinegar. Mostly the powder is on the black plastic handles of steak knives and teflon pans. Sometimes it's just over crowding or a large pan blocks the upper arm of the dishwasher---still the vinegar cure is good to do just as a matter of course for a dishwasher.
Now, I'm going to have to look and see if the stuff I'm using is phosphate free.