[Boatanchors] white dust on aluminum

[Chuck Gallup]

I once bought a large quantity of Mil Surplus Aluminum Rigid Coax . The lower 
ends were in a container that had 2 to 3 inches of water. When I took them out 
of the water the ends just fell off. After drying out the ends turned into the 
white powder and were useless. Be careful that you don't have holes thru the 
metal.

Best,
Chuck  K7NKS



----- Original Message ----
From: J. Forster <jfor at quik.com>
To: Jim Wilhite <w5jo at brightok.net>
Cc: Boatanchors Mail List <boatanchors at mailman.qth.net>
Sent: Thu, June 9, 2011 5:41:50 PM
Subject: Re: [Boatanchors] white dust on aluminum

Is the item a casting? I think some casting alloys contain a lot of
magnesium, which corrodes more than alloys with less Mg?

Best,

-John

================

> Any mildly acetic solution should remove the "dust" which is corrosion
> due to oxygen breaching the protective layer on the aluminum.  Muriatic
> acid or vinegar either should remove the layer.  I would try the vinegar
> first along with a Scotchbrite pad.
>
> Once the corrosion is removed use something to seal it against the air.
> Clear spray made by Kryon will work but do be careful because a scratch
> will expose the surface again.
>
> Jim/W5JO
>
> ----- Original Message -----
>
>
>
>>I have a piece of  equipment in an aluminum case that has been in a
>>very humid
>> environment and was sweating due to condensation  in the shipping
>> crate. The
>> instrument case has suffered from the condensate.
>>
>>
>> The aluminum, after drying, has a coat of aluminum dust or powder that
>> needs to
>> be removed. It is a very valuable instrument and can be very useful in
>> the shop
>> and shack.
>>
>> If anyone can tell me how to remove the white powder that I believe to
>> be
>> oxidation, I will greatly appreciate it. Chemistry was not my strong
>> subject.
>> Come to think of it, I don't think I had a strong subject.
>>
>> Assisting with your chemical expertise will be appreciated. 73, John,
>> K5PGW
>>
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