[TowerTalk] Re: Chromate Treatments

[Bowen, Arlan]

At 01:43 AM 9/22/97 -0400, you wrote:
>I have heard of something that is supposed to
>help to reduce the corrosion of antennas from
>salt air.  Called Iridite Solution.
>
>Does anyone know anything about this?
>
>What it is?
>Does it work?
>Where to get it?   

Iridite is a trade name for a "supplementary chromate treatment". There are
several suppliers who sell under different trade names, which do not come to
mind at the moment. The process is also covered by a military specification,
MIL P (5 digits).

As applied to aluminum, the process generally calls for immersion in a
cleaning solution such as sodium hydroxide or an acid, followed by a rinse
in "clean" (no minerals) water followed by dipping in or painting with the
chromate solution. Elevated temperatures are usually used to speed up the
process. Dye is frequently added to the solution to give a "gold"
appearance, as the base product is difficult to otherwise detect, except by
chemical analysis. 

The processed part, after drying, is quite resistant to corrosion caused by
atmospheric elements. It has very low abrasion resistance. It generally
provides a good base for painting of aluminum. It is also used as a
supplementary treatment for plated steel parts.

Portions of the process are toxic. Suspect you can find information
somewhere on the web under metal treatment or similar topics and of course
in your local library. It is not a process that should be used by the "home
brewer".

We used the process in my "other life" for treatment of aluminum parts. The
health and safety folks eventually made us remove the facility because of
toxicity problems, difficulty in keeping the bath chemicals in balance and
further problems with disposal of the chemicals.

INK  N4OO


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