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  1. #1
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    Aug 2009
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    Default Help Identify Substance on Metal Door Frame

    Commercial building inspection. Aluminum door frame and threshold. Bottom of door frames are rusting and threshold is showing signs of deterioration. This white substance was built up in several areas. Could it be leftover ice melt? It was the consistency of wet laundry detergent. Thanks.

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  2. #2
    Join Date
    Mar 2007
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    Default Re: Help Identify Substance on Metal Door Frame

    Probably aluminum oxide or whatever corroding aluminum makes when the aluminum corrodes into that stuff.

    Those are most likely aluminum, not steel, so it would be corrosion, not rust ... but ... I guess "rust" is a type of "corrosion" ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
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    Spring Hill (Nashville), TN
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    Default Re: Help Identify Substance on Metal Door Frame

    Yes, ice melt salt will do exactly what you have in the photos.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

  4. #4
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    Default Re: Help Identify Substance on Metal Door Frame

    Quote Originally Posted by Scott Patterson View Post
    Yes, ice melt salt will do exactly what you have in the photos.
    Is that the left over salt used for melting the ice, or is that the aluminum corrosion the salt causes? Or is that possibly both?

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  5. #5
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    Bennett (Denver metro), Colorado
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    Default Re: Help Identify Substance on Metal Door Frame

    If it came from the aluminum, you'll see deterioration of the aluminum. I lean toward salt. Salt doesn't get washed out from the edges of the frame as easily and since salt "attracts" moisture, there can be efflorescence along the edge of the frame over time. Aluminum oxide is usually like talc in my observations and not as coarse as detergent.

    If you choose not to decide, you still have made a choice.

  6. #6
    Join Date
    Feb 2008
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    Caledon, Ontario
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    Default Re: Help Identify Substance on Metal Door Frame

    Could also be Urea or Calcium Chloride, both of which are deicing products.

    Calcium Chloride is also used for dust control on dirt roads to keep the dust down and harden the surface.

    And Urea is also a fertilizer.

    FWIW.


  7. #7
    Join Date
    Feb 2008
    Location
    New York
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    Default Re: Help Identify Substance on Metal Door Frame

    Iron oxidizes (rust).

    Aluminum oxidizes too. In the form of a dull whitish patina that covers the material. The haze then protects it from further oxidation. Same thing with silver (tarnish), brass, etc.

    When we polish these metals, the black that dirties the rag is the oxidation.

    Steven Turetsky, UID #16000002314
    homeinspectionsnewyork.com
    eifsinspectionsnewyork.com

  8. #8
    Join Date
    Mar 2007
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    Default Re: Help Identify Substance on Metal Door Frame

    Quote Originally Posted by Steven Turetsky View Post
    Iron oxidizes (rust).

    Aluminum oxidizes too. In the form of a dull whitish patina that covers the material. The haze then protects it from further oxidation. Same thing with silver (tarnish), brass, etc.

    When we polish these metals, the black that dirties the rag is the oxidation.
    Iron also rusts through, and disappears over time as iron oxide.

    Aluminum also corrodes through, and disappears over time as aluminum oxide.

    I've many iron items "rusted out" and many aluminum items "corroded through".

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  9. #9
    Join Date
    Aug 2009
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    Oklahoma
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    Default Re: Help Identify Substance on Metal Door Frame

    Thank you gentlemen!


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