[Milsurplus] Painting Aluminum - BC-348 in particular

[Gene Smar]

Gents:

     The strong alkalis mentioned below reminded me:  When I was a Novice 
(back when you listened to radio via candle light), I read in 73 Mag (I 
think) about preparing aluminum for painting.  The suggestion was to soak 
the piece in a bath of Drano dissolved in hot water.  Obviously this had to 
be done outdoors.  I used the process on a project box for a 12 VDC power 
supply before I painted it with gray primer.  I still have the box/PS today 
and the surface is almost as good as new - just a few scratches from several 
moves through the years.  You might want to try the following on a scrap 
piece of aluminum -JIC.

    I Googled <aluminum etching drano> and found a couple of sources that 
described a process similar to what I remembered.  But because this is some 
what hazardous material, you ought to decide for yourself if you want to 
take this approach.

     Caveat Amateur.


73 de
Gene Smar  AD3F



----- Original Message ----- 
From: "J. Forster" <jfor at quik.com>
To: <gl4d21a at juno.com>
Cc: <milsurplus at mailman.qth.net>
Sent: Thursday, May 13, 2010 11:23 PM
Subject: Re: [Milsurplus] Painting Aluminum - BC-348 in particular


>> Hutch:
>>
>> There are several problems with crackle paint on aluminum.  One is making
>> it stick, and that is where zinc chromate primer came in.  Not sure it is
>> still legal to sell, but it used to be available in spray cans, and 
>> normal
>> can quantities.  The second problem is yours, incompatibility between
>> primer and paint.
>>
>> The first problem is overcome with surface preparation, some sort of
>> chemical bath which I have forgotten the details of.  Strong alkali, I
>> think.
>
> Sodium or Potassium Hydroxide will etch the surface of aluminum to a matte
> finish, helping the paint adhere.
>
> -John
>
> ================
>
> The second is to use primer and paint from the same manufacturer
>> and from the same product family, information which the manufacturer
>> should publish.
>>
>> Google is your friend.  Or Bing if you swing that way.
>>
>> 73,
>> George
>> W5VPQ
>>
>> ---------- Original Message ----------
>> From: John Hutchins <olegerityincj at austin.rr.com>
>> To: Milsurplus at mailman.qth.net
>> Subject: [Milsurplus] Painting Aluminum - BC-348 in particular
>> Date: Thu, 13 May 2010 21:46:44 -0500
>>
>> Group  -
>> Good evening -
>>
>> The black wrinkle tex paint I applied many years ago never cured it
>> remained soft/slightly sticky.  So I am removing the bad paing job and
>> starting over.
>>
>> That being said I noticed that there is a green chromate primer layer;
>> Is this a paint or a immersion coating?
>>
>>
>> Thanks
>> Hutch
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