Andy, If you cannot acquire a 9k hard white solder, try using the
medium white for he next karat up, or as high a karat as you can find
which still falls below the melting temp of your 9k material.
I assume you want the harder material in order to avoid the solder
seam eroding out when you finish the piece. Otherwise, I don’t
think a married metal situation as you describe has to have such a
strong join.
As for actually making the join, I have a suggestion which,
depending on the width of your mating surfaces, may help. In the
Bench Tricks column in the May 02 issue of JCK, an approach used in
sweat soldering by Wayne Lenkeit, of Lenkeit Manufacturing in
California, was described.
His technique, which he uses to obtain clean solder seams in overlay
work is this:
Bur a series of small depressions on the back of the smaller piece;
fill these depressions by flowing solder into them; sand the
filled depressions level with the metal’s surface; prep for
soldering; place piece as desired and heat until the solder flows to
the edges of the seam.
I have found this works great for any number of jobs, not just
overlay. Instead of taking forever to bur a series of varied depth
depressions, however, I use a centering drill of the appropriate
diameter to drill a number of holes to a more precise depth (and a
whole quicker than trying to ball bur them), fill with solder as
above, sand as above, prep, place and heat.
With a little practice you can get perfect solder seams with
absolutely no cleanup, and you can use fixturing techniques to hold
things in place because the pieces don’t move in relation to each
other at all when flow temp is reached.
If you’ve got enough room on mating surfaces to place the holes you
might give this a try.
Les Brown
L.F.Brown Goldwork, Inc.
Kalispell, MT 59901