Homebrew PCBs

Leon Heller, G1HSM
http://www.geocities.com/leon_heller
----- Original Message ----- 
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, May 12, 2004 6:06 PM
Subject: Re: [Homebrew_PCBs] Blackening copper


> On Wed, 12 May 2004 11:04:54 +0200, Stefan Trethan <stefan_trethan@...>
> wrote:
>
> > Strange question, i know..
> >
> > any ideas how to chemically blacken the copper on a pcb (copper only,
not
> > epoxy).
> >
>
> found something:
>
> <http://www.cpachem.com/en/madchem/06.htm>
>
> Have no sodium thiosulfate at hand, but did read somewhere else
> it might work with sulphur, have enough sulphur so i will try....

Sodium thiosulphate (hyposulphate) is the old 'hypo' that used to be used as
a photographic developer.

Leon