[TheForge] Working copper

[Dave Brown]

At 08:31 03/12/02 -0500, Don Plummer wrote:
>Morning, Folks
<snip>
>I have  volunteered to make a couple things for the Mastermyr exhibit at the
>ABANA conference and finally getting to it. To wit: a cauldron
<snip>
>It has to do with what I know as 'cramping',
<snip>
>The question is this: I have had some tell me that both edges need to be
>cramped or tabbed.
<snip>
>Can anyone share their experiences or recommendations with me on this
>process? Also re prep for soldering. The cauldron is thin, being made of
>about .020 copper and is about 20" in diameter with six separate pieces used
>to make up the sides and thus require this edge joining.

Don,

I have seen artifacts that show that both ways were used.  However, the 
cramping that I have seen most often is the method of making tabs on one 
edge only.  The pieces I refer to were early New England pieces and may or 
may not represent the procedure used around the time that the items in the 
Mastermyr Find were made.

>Also, could someone make recommendations re flux and solder for this joint?
>All I have around is some Stay-Clean flux and some Canfield no lead solder.
>But I am beginning to suspect that some lead solder might be better.

The Stay-Clean and no-lead solder should work, but generally takes more 
heat to get the solder to flow well.  Since this caldron won't be used for 
food, I think you will find that 50-50 tin/lead solder is easier to work 
with.  The Stay-Clean or even No-Korode will work.  If you wanted more 
authenticity to the fluxing, then pine rosin would be my flux of 
choice.  It's surprising how well this works and in my tin work I prefer it 
to any of the paste fluxes.  But choice of flux probably doesn't matter in 
the long run, so use what you have.

You might also want to consider tinning the tabs before final fitting and 
jointing.

Dave Brown