Homebrew PCBs

Leon Heller wrote:
> ----- Original Message ----- 
> From: "Russell Shaw" <rjshaw@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Saturday, May 15, 2004 8:10 AM
> Subject: Re: [Homebrew_PCBs] Re: Blackening copper
> 
>>Leon Heller wrote:
>>
>>>----- Original Message ----- 
>>>From: "Steve" <alienrelics@...>
>>>To: <Homebrew_PCBs@yahoogroups.com>
>>>Sent: Wednesday, May 12, 2004 7:12 PM
>>>Subject: [Homebrew_PCBs] Re: Blackening copper
>>>
>>>>--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
>>>><stefan_trethan@g...> wrote:
>>>>
>>>>>Strange question, i know..
>>>>>any ideas how to chemically blacken the copper on a pcb (copper
>>>>only, not epoxy).
>>>>>
>>>>>For optical purposes, not electric. should be even colored.
>>>>
>>>>I found something at an art store a few years ago called "Liver of
>>>>Sulphur" which I used to blacken copper for antiquing purposes.
>>>>
>>>>No idea what was in it, or where I have the bottle now to check. Google.
>>>
>>>As someone else said, it's potassium sulphide. IIRC it's made by heating
>>>potassium metal and sulphur. This could be dangerous, BTW.
>>
>>Maybe reacting potassium hydroxide with sulphuric acid could give
>>something.
> 
> That will give potassium sulphate, not the sulphide.

Thought so. But isn't there a heating/reducing step to turn it
into sulphide?