Letter 41073

Alodine Coating  

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One of my customers is returning parts to us to trim the ends. The parts have been cadmium plated already and they state that "After trim, vendor needs to alodine exposed ends".

In my research on Alodine it appears that it is not just something that can be painted on the ends and that it is for Aluminum. These parts are made out of music wire.

Is there a pen or paint brush method that can be used to Alodine the cut ends? And can alodine be used on music wire?

Thank you,

Terry Austin
spring manufacturer - Stanton, California

Alodine is a Henkel tradename for chromate conversion coating processes. Although Henkel certainly has chromate conversion coating processes for aluminum that go by the Alodine tradename, they have chromate conversion coating processes to be applied to Cadmium plating that go by the Alodine tradename as well. But in any case you cannot chromate conversion coat bare steel.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

I have been researching Alodine and wonder if Trisodium Phosphate [link is to product info at Amazon] (TSP) can be used prior to using Alodine with the same results as other methods?

Bob

Bob McKellar
- Entiat, Washington

Hi, Bob. I wouldn't do that. It may be possible to get the cadmium plated surface active by scrubbing it with TSP and a tampico brush (especially if it's more of a paste so it has some polishing action), but I think you don't want to scrub cadmium because it's a biocumulative poison.

Regards,

Ted Mooney finishing.com Brick, New Jersey