[TheForge] sealing copper pee patina

[Andrew Vida]

Peter Hirst wrote:
> I am not so sure about copper patinas not being permanent.  You se a lot 
> of copper roofs that stay a nice green indefinitely, (St Matthews 
> cathedral in DC, for an AMerican example) and I am sure no one is up 
> there periodically, uuh, renewng the treatment. 

	Those finishes are constnatly renewing themselves, meaning that the 
pure copper underneath is constantly being consumed.  That is not 
permanent by any definition I would consider valid.

 > I have a commper
> sculpture in my shop yard that was treated in this way that has remained 
> stable for years.   Bears more research, I think.

	It may take decades or even a century or more, but eventually that 
sculpture will wash a way.