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Thread: Aluminum foil

  1. #1
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    Aluminum foil

    For some new woodworkers that may not know, if you wrap a flat file with aluminum foil, the file will not rust.
    Galveston County Texas is rough on files.

  2. #2
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    Why is that? Aluminum foil keeps out moisture? Chemical reaction?

  3. #3
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    Aluminum foil sprayed with WD40 is also a very good way to scrub away rust.

  4. #4
    Quote Originally Posted by Pat Barry View Post
    Why is that? Aluminum foil keeps out moisture? Chemical reaction?
    I'm just guessing but a properly wrapped aluminum foil could be air tight and keep out moisture.

    Mike
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    It possibly serves as a sacrificial layer. It will get oxidised before steel.

  6. #6
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    Aluminum foil not going to be much of a sacrificial material compared to steel. Aluminum oxixizes rapidly but doesn't build any significant thickness. It is a very effective moisture barrier though as mentioned by others.

  7. #7
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    Just try it. You will be amazed.

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    I suspect it has something to do with aluminum's excellent thermal conductivity (only three metals Ė gold, copper and silver Ė are more thermally conductive) moving heat into the files without getting them wet from condensation/dew and thus rusting them...

    On the other hand, you could probably do the same thing with plastic Saran wrap, which ain't very thermally conductive. Or light oil/kerosene.

  9. #9
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    Quote Originally Posted by Jacob Reverb View Post
    I suspect it has something to do with aluminum's excellent thermal conductivity (only three metals Ė gold, copper and silver Ė are more thermally conductive) moving heat into the files without getting them wet from condensation/dew and thus rusting them...

    On the other hand, you could probably do the same thing with plastic Saran wrap, which ain't very thermally conductive. Or light oil/kerosene.
    Lowell is right. Itís called cathodic protection - based on electrical conductivity, not thermal.

    The dissimilar metals form a battery, where in this case the aluminum is the sacrificial anode.

    Itís common method to protect ships hulls, pipelines, storage tanks, etc... And generally itís not necessary to 100% wrap the steel in the aluminum to protect it; the two just need to have good electrical contact. (But wrapping it canít hurt!)
    Molann an obair an saor.

  10. #10
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    Hmmm.... Can I wrap my entire table saw top in foil when not in use then? ha ha
    If at first you don't succeed, redefine success!

  11. #11
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    This explains why my head doesn't rust.

  12. #12
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    Quote Originally Posted by Stan Calow View Post
    This explains why my head doesn't rust.
    LOL. Also good for blocking the mind control from aliens or 5G!
    If at first you don't succeed, redefine success!

  13. #13
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    Quote Originally Posted by Malcolm McLeod View Post
    Lowell is right. It’s called cathodic protection - based on electrical conductivity, not thermal.

    The dissimilar metals form a battery, where in this case the aluminum is the sacrificial anode.

    It’s common method to protect ships hulls, pipelines, storage tanks, etc... And generally it’s not necessary to 100% wrap the steel in the aluminum to protect it; the two just need to have good electrical contact. (But wrapping it can’t hurt!)
    Well, and you also need to submerge the dissimilars in an electrolyte. I'm not sure a bit of condensation on the surface of the aluminum foil is gonna work, particularly if you completely wrap the steel file. (Also, it's not differences in electrical conductivity, but rather differences in electrode potential.)

    Yeah, I run boats in the ocean and am familiar with galvanic corrosion. It eats stuff up. A pencil line across a stainless prop shaft is a good way to lose a wheel.
    Last edited by Jacob Reverb; 07-12-2019 at 7:47 PM.

  14. #14
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    Don’t know a lot about this, but seems like some sort of electrolysis (sp.?)

  15. #15
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    Quote Originally Posted by Jacob Reverb View Post
    Well, and you also need to submerge the dissimilars in an electrolyte. I'm not sure a bit of condensation on the surface of the aluminum foil is gonna work, particularly if you completely wrap the steel file. (Also, it's not differences in electrical conductivity, but rather differences in electrode potential.)

    Yeah, I run boats in the ocean and am familiar with galvanic corrosion. It eats stuff up. A pencil line across a stainless prop shaft is a good way to lose a wheel.
    I may be getting way out in the weeds and I am certainly stretching the brain cells pretty thin here, but there are differing quality electrolytes. Saltwater obviously is decent, but I dimly recall air can serve as an electrolyte too, just a really, really poor one....???
    Molann an obair an saor.

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