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Thread: Lowers: teflon over anodizing vs. just anodized

  1. #11
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    If you can actually leave a mark in the anno with your fingernail then something is waaay outta spec. The anodized surface on an aluminum part is a lot harder than the aluminum itself. My guess is that the mark you're seeing is parts of your fingernail being scratched off onto the annodizing like a piece of chalk on chalkboard.

  2. #12
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    Quote Originally Posted by mkmckinley View Post
    If you can actually leave a mark in the anno with your fingernail then something is waaay outta spec. The anodized surface on an aluminum part is a lot harder than the aluminum itself. My guess is that the mark you're seeing is parts of your fingernail being scratched off onto the annodizing like a piece of chalk on chalkboard.
    Yes, I didn't mean to sound like I actually scratched the anodizing.

    But the anodizing on the DD is shinier and very smooth, doesn't leave a mark when I rub a fingernail.

  3. #13
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    How old is your DD receiver?

    I bought mine a few months ago, and I've found it's a pretty flat black. I wonder if there is a difference in batches.

  4. #14
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    I don't know, I think it differs from mfg to mfg, the anodizing like I have on my LMT is more porous and holds oil, where the DD is smooth and doesn't hold oil. I just don't know what "kind" of anodizing they (and other top tier mfg) use.

  5. #15
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    Quote Originally Posted by Artiz View Post
    I don't know, I think it differs from mfg to mfg, the anodizing like I have on my LMT is more porous and holds oil, where the DD is smooth and doesn't hold oil. I just don't know what "kind" of anodizing they (and other top tier mfg) use.
    That textural difference isn't due to the anodizing process. It's due to the metal surface finish prior to anodization.

  6. #16
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    Anodizing is a surface conversion process. Half of the coating thickness goes into the surface and half of it "grows" the surface. Hard coat anodizing is full of millions of microscopic cracks. To get color it is dyed and the dye goes into the surface. For good corrosion protection it needs to sealed. IIRC the milspec calls for nickle acetate sealer - a fairly old technology.

    A Teflon sealer, especially if applied as vacuum impregnated, is an excellent protective layer. If the surface is sealed this way it probably won't hold paint very well but it should be very corrosion resistant. The Teflon finish is used on high end marine hardware.

  7. #17
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    Under what conditions does one need to worry about aluminim corroding?

  8. #18
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    Bushmaster advertises that they apply a nickel acetate sealant over their finishes. Not really sure of the pros/cons of that particular application, but they advise not to rub down the exterior with any solvent that would affect nickel.

  9. #19
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    DBR, very good info. It sounds like the mil-spec is another instance of a specification being frozen in time at the best reasonably attainable option when it was written, which was a long time ago.

    I'm still waiting to hear any real downsides of teflon over anodizing. I was wondering if it might interfere with rollpins staying in place, but I've never heard of that being a problem with the commercial receivers that use it, nor has anyone so far posted that it is an issue.

    Quote Originally Posted by mkmckinley View Post
    Under what conditions does one need to worry about aluminim corroding?
    Aluminum corrodes very fast in a saltwater environment. Far away from salt, it's naturally corrosion resistant because it forms a layer of aluminum oxide on the surface. Anodizing forms that same layer more thickly and under more control.
    Last edited by SomeOtherGuy; 12-26-10 at 13:48.

  10. #20
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    Quote Originally Posted by mkmckinley View Post
    Under what conditions does one need to worry about aluminim corroding?
    That's what I say when I see these pictures or AR's that seem to have fallen in the oil bucket... senseless use of oil.

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