In your message dated Friday 27, December 1996 you wrote :
> It seems that entropy does not govern when it comes to copper in HASL. 
> Removing the dross significantly affects copper levels with the
> occasional addition of solder bars.
> Has anyone found a way to recycle tin/lead 'in house' and purify the
> solder for reuse?  
> Chemically or metallurgically there has to be a way it seems. 
> 
I am not sure of the mechanism but holding the solder pot at around 180 deg C 
overnight will cause copper to oxidise/crystallise out on the surface. It can 
then be scraped off with the dross. If this is done daily you can keep the 
copper level consistently low and avoid changing the solder. This is an 
automatic procedure on our CEMCO Quicksilver machine.

Happy New Year 
Paul Gould
EMail [log in to unmask]

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