[TheForge] copper goo or paste [longish response]

[Andy Vida]

Gladish Family wrote:

> I'm pretty happy with the size of the seams (barely visible) but she'd like
> them to disappear if possible.
> Andy G.
> 

	You may want to explaing to her that "goo" of just about any 
	form will fail in time, especially when it is subjected to 
	wetness, etc.  How much time in the kitchen, I have no idea
	though I'm sure it's probably years

	Another thing you can do, but this would be a major undertaking
	in terms of time and effort, would be to silver solder the 
	seams.  Back in the days when I did such things for a living, I
	may have been able to solder such a seam with a line of silver 
	no wider than 0.001" and often less, over the length of the 
	joint.  Longest seam I recall ever doing wasn't more than 
	perhaps 6 or 8 inches, so a 22 (or whatever) inch seam would 
	pose a very significant filing challenge to even an expert 
	filer and the soldering would take a good torch hand, but it 
	could definitely be done with patience,	some good files, a 
	scraper, and Dy-kem hi-spot.  If, by any wild chance you 
	attempt this, I will give you a trick to help with the
	soldering.  Solder from the underside and chamfer the sheets 
	ever so slighty as so:

	
                __________   __________
               |          \ /          |
               |           |           |
               |___________|___________|

	Set the solder into the groove.  Another thing you can do, and
	again it's extra work, is to make your own copper solder.  
	Basically you are making a shibuichi alloy, perhaps 15% silver,
	which will lower the MP of the copper, allowing you to be not
	nearly as careful during joinery.  Draw into wire or pound into
	something vaguely resembling sheet and cut into strips, get out
	the O-A or prestolite torch, tack every 4 inches and fill in 
	the rest.  You will need to rig up a makeshift jig to align the
	sheets accurately.

	The chamfering will hold most of the solder and control the
	flow between sheets, making for far less cleanup later.  It
	also increases surface area and in this case I think will
	make for a better joint.

	This will be a lot of extra work and you must not, IMO, do it
	unless the client is willing to pay for it, which they will
	almost certainly not be unless, by God, they are actually,
	<gasp>, *reasonable*.

	I think TIG's the best answer.  Faster by far, the result
	should ultimately prove perfect, and won't rupture the
	client's wallet.  If you don't have TIG, find a shop.  What
	could it cost for, say, 90 inches of joinery?  Probably not
	as much as the time you will waste screwing around trying
	to find "goo", putting in on, finding out it doesn't work
	this way or that... more experimentation... generally
	unsatisfying outcome... blah blah blah...  

	If you have to use "goo", then may I recommend clear epoxy?  
	Just do an ass-kicking job of filing the joints true and 
	thin and the epo will do the rest.  It will take up the 
	color of the surrounding metal and I seriously doubt it 
	will present a more onerous aesthetic than copper colored 
	material and I would daresay probably a damned sight better.
	Don't worry about making the seams absolutely straight.
	File one side of a joint as flat as you can without losing
	anything significant in terms of sheet length.  Dye the
	other edge with hi-spot and rub together with about 1/4"
	stroke back and forth.  Ignore the high spots on the
	"reference" edge and file/scrape the high spots down on the
	other one.  If you're good with your files, you can do
	this a lot faster than you think.  Also, bevel the edge
	so that the sheets meet at a VERY thin edge, rather than
	the entire thickness of the sheet, as so:

                 ___________________  _____________________
                |                   ||                     |
                |                  /  \                    |
                |_________________/    \___________________|

				~5* bevel

	I'm assuming you're using contact cement to fix the sheet
	to the counter tops.  In that case, prepare the cement for
	two sheets, leaving 1/8" at the seams without cement. Goo
	up epoxy onto the 1/4" bare strip on the wood at the seam
	location. Lay the sheets, leaving the other end of the 
	second sheet under some teflon or other non-stick blocks 
	so you can goo up the next joint with ease.  Epo will ooze.  
	Use wax paper atop the seam and place heavy weights all 
	along the joint and let the glue set.  Move on to the next 
	joint.

	When set, use solvent to take down the epoxy on the surface,
	then buff out.  If you've gotten it right, the seams will be
	as close to invisible as all good reason can expect.  Epo
	is pretty tough and should last, but I don't know how it 
	or any other similar material will hold up to the kitchen
	environment, but I'm sure it will be years at the very least.


	Does any of this make sense?

	Good luck.

	-Andy