Rust Or Corrosion Of Tin Or Aluminum Cans

Discussion in 'Science & Nature' started by Ken Anderson, Jun 27, 2021.

  1. Ken Anderson

    Ken Anderson Senior Staff
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    Years ago, grocery store cans were generally made of tin, or at least mostly tin. When left outdoors, they would rust and disintegrate into pretty much nothing in a fairly short time. However, I understood that tin cans were replaced by aluminum cans, and that aluminum does not rust.

    However, I placed an unopened can of something that had expired in my compost a few years ago and now that I am harvesting that compost pile, I came across it, and there was practically nothing left of it. There were large holes all over it, and what was left wouldn't even hold up to finger pressure.
     
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  2. Bobby Cole

    Bobby Cole Supreme Member
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    It may not rust but it will definitely corrode. There are a few ways it can corrode like an acidic PH level in your soil and a lot of water will do it over time especially if the protective surface of the aluminum is scratched or damaged.
     
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  3. Ken Anderson

    Ken Anderson Senior Staff
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    I don't know about the acidic level but the water would certainly be there because it has been out there during a couple of winters, and all the snow that falls on the pile melts eventually. Plus, I water my compost pile from time to time.
     
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  4. Bobby Cole

    Bobby Cole Supreme Member
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    About the only thing that keeps the aluminum cans safe for food and drinks is the oxide coating on the metal. It’s hard to do but once that stuff gets a deep scratch or bent any number of things can hurt the can.
    In the restaurant business, when ANY kind of can whether it is tin or aluminum is bent or damaged the contents and the can has to be thrown out or returned to the seller for fear of food poisoning.
    A damaged can on the shelf when the health inspector arrives will be taken very seriously and could cost the restaurant some major negative points or grades.
     
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  5. Don Alaska

    Don Alaska Supreme Member
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    I don't put anything metallic in my compost as I don't want to add large amounts of metals to my soil. Aluminum will also corrode when subjected to many salts, including NaCl. My kids used to get a kick out of melting aluminum cans inside steel (tin) cans in a hot campfire. I think they even poured the melted aluminum into molds occasionally to make "stuff".
     
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  6. Ken Anderson

    Ken Anderson Senior Staff
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    I don't generally, either. I would consider this as a scientific experiment. I had anticipated that it might have been crushed, and even that it might swell or pop open due to a combination of heat and spoilage, but I didn't expect to find almost nothing left of the can itself. It was still in the shape of a can, only there were as many holes as closed spaces.
     
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  7. Frank Sanoica

    Frank Sanoica Supreme Member
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    @Ken Anderson

    Years ago, we called them all "tin cans". Reality was, virtually NO CAN were made of tin at all, because so many foods attack tin and "eat it away", particularly acidic foods, tomatoes, stuff containing vinegar, etc. Cans were made of STEEL, which of course rusts easily, so coatings were devised for the insides of cans. One of them was Tin! This all depended on the type of food to be stored. As years went by, newer plastic type coatings prevailed.

    Surest way to tell: check your can with a magnet. MOST will prove to be steel; tin is non-magnetic.
     
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  8. Ken Anderson

    Ken Anderson Senior Staff
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    Some of the odd sodas that I order on Amazon are not in returnable cans, so they would ordinarily be disposed of in the regular trash. However, I've noticed that some brands are in cans that appear to be made of aluminum or a blend of aluminum and something else, only thinner and with a different feel to them than the ordinary soda can.

    I have found that if I put these empty cans in my fire pit while burning wood, charcoal, or anything else that burns for quite a while before burning out, they disappear. I don't find anything in the ash that resembles metal. The cans just seem to disappear or turn to ash.
     
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