If it is aluminum it should not be used for food stuff. I don't think it is worth your time and effort. If it is aluminum make sure your family or heirs know the dangers.

Personally I would destroy it to make sure someone doesn't end up using it for food.

Emma, you are mistaken in thinking that aluminium is not safe to be used for food. Many pots, baking pans and serving dishes are made from aluminium- and aluminium foil is widely used for wrapping food. If you're referring to the alleged "connection" between aluminium and Alzheimer's disease, that study was shown to be flawed many years ago (they made up a lot of their data). It is no longer thought that there is in fact any connection.
emmi, without knowing exactly what the metal is, and what product you used on it, there is no way anyone can say whether or not your dish can be restored.

It sounds like this bowl has a lot of meaning to you. Certainly worth your time and effort!! Wish I could help, can only wish you luck.

What kind of polish did you use, that ruined it?

1930's, flowers, there were a lot of serving pieces made from stamped aluminum then.

Aluminum is fine for a lot of things. but if you cook acidic liquids in then, they will etch and discolor. Sounds like this is more of a serving piece, though.

A picture will be very helpful. Do you have a scanner? sometimes that can be used in place of a camera.

Does it look like this?

Here is a link that might be useful: 8 1/2 inch aluminum bowl

Does it look like this?

Yes, it looks very much like it. The stamp on the bottom shows 2 men standing over an anvil, with 230 D stamped under it. The diameter is almost the same. The design is not quite as heavy as the one in the picure, but this seems to be almost the same dish. Thanks! I'm not sure how to restore it, though. Can aluminum be re-coated, like silver? Somehow I doubt it. :o(

No. Aluminum in these pieces is solid, not plated like silver plated ware. We still need a photo to see what it looks like now. And again, what polish did you use? I want to find out what kind of chemical reaction it had with the metal.

The ridiculous thing is, I can't remember what kind of polish or cleaner I used. (It was a while back.) I have a sinking feeling it was Brillo. I must have had the idea that it would remove the dullness and restore some shine. As Rudyard Kipling would say, "Not so, but far otherwise." I love the bowl, and am thinking of ordering the one newhomebuilder linked me to. It will not have the sentimental value, of course, but it would be nice to have something from that era.

Did you buy it? ...it's been sold.

Yes - I'm the one who bought it!! ":o) And I will be VERY careful about cleaning it properly....

Just so you know, aluminum will never get a high polish or very reflective surface like silver. These plates looks best with the original satin finish. When they were popular, they usually have a hammered finish as a background texture.

Raw aluminum left outside will get a rough spotty texture. Growing up everyone I knew had an unpainted aluminum storm door, and they all got like that. There is a special cleaner to remove that. But I have never seen that kind of oxidation on a piece kept indoors, no matter how old.

A heads up to anyone who buys those retro aluminum pitchers (the ones with aluminum glasses to match), refrain from sticking them in dishwashers if you want to preserve their finish as well.

Good reminder. Aluminum is very soft, and harsh dishwasher detergents can etch the metal. I grew up with a set of those glasses! But we didn't have a dishwasher. The colored ones have an anodized finish: aluminum is a metal that can react electrically, and turn pretty colors. I did it once in a metals class. But the colored layer is very thin.

Thanks, all, for your input! And my bowl does have the hammered finish (I was tempted to get hammered myself after seeing what I'd done). I'm mad at myself for not thinking things through before tackling the cleaning job, but I've learned my lesson, for sure. The dish is still perfectly useable, but just not pretty. I'll take very good care of the "new" one.

Aluminum can be polished to a mirror shine, but takes more upkeep than any other common metal.

The shine on that bike is AWESOME!!