Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "lcdpublishing" <lcdpublishing@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 07, 2006 2:55 PM
Subject: [Homebrew_PCBs] Chemists? Ferric Chloride and Aluminum?


> Hi guys,
>
> Perhaps one of you chemistry guys knows what happened here. While
> etching a board, I got to thinking about how the Ferric Chloride
> stains some metals (and wood, and other things) black. Always one to
> try things, I dipped an aluminum bar in the stuff for a few seconds.
>
> When I pulled it out, it had what appears to be rust scale on it like
> crazy! I assume this to be bits of Copper and not rust, but I was
> wondering if someone could explain what happened there? I don't think
> it was electrolysis - no electricty going through the mess.
>
> Yet, somehow, the copper seemed to attract to the aluminum - it didn't
> stick though. A rinse in water removed it quickly. The aluminum did
> turn gray in color and not black like i had hoped - so it was a failed
> experiment. But, it sure was interesting and raised a few questions!

You can get an electrolytic effect (a battery) by putting two dissimilar
metals in an acid solution, and iron can be coated with copper just by
putting it in copper sulphate solution: iron is dissolving and being
replaced by copper. Perhaps that was happening in your case.

Leon

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