Am I correct in thinking that if I substitute high melting point
silver solder for enamel melting point silver solder that the
joint will be even stronger and less liable to discolour as the
Silver content in the solder will be higher ? and if I adopt this
approach are there any down sides to it, other than it needs
greater heat control when soldering.
You would need to specify the particular alloys you mean when you
say "high MP Ag solder" and "enamel MP Ag solder" Paul.
If you mean the generally used "hard" Ag solder ( 75/22/3 Ag/Cu/Zn )
and eutectic Ag solders ( 72/28 Ag/Cu ) respectively and intend to
enamel over the joint the answer is no.
The 72/28 Ag/Cu eutectic alloy is the best choice for use with 925
Ag ( I'm assuming that's what you're intending to enamel - if you
were using 999 silver you could solder it with ordinary Sterling )
1/ contains no Zn which is just a bloody nuisance when enamelling
2/ melts at a precise temperature - 778 deg C
3/ flows beautifully & leaves no cap - essentially becomes
indistinguishable from the Sterling base and would appear not reflow
on subsequent normal firings.
Certainly it's possible to enamel successfuly over this material.
Use the smallest amount necessary to effect the join and depletion
enrich edequately after soldering.
The "hard" 75/22/3 alloy has a softening point ( about 740.5 deg C )
and flow point (787 deg C ) not a melting point so is consequently
still "slushy" below the "setting" point of most enamels - they crack
and/or break away.
In cooling and hardening the enamels can also deform the
Almost the same things can be said of the stuff I've touted for most
of my enamelling life - the 80/16/4 alloy ( SP 721 deg C, FP 810 deg
C ) - the so-called "IT enamelling Ag solder". Until a couple of
years ago I still persevered with this stuff in spite of the fact
that I could only make it work in a so-so fashion.
I knew that silver-filigree makers had used the eutectic alloy
successfully for a thousand years (bit of artistic hyperbole here )
and Eastern European enamellers had borrowed their materials and
techniques to make their stunning plique-a-jour but I thought I knew
better. I looked at the Flow Points of the various alloys and thought
that higher must naturally be better. I was ignorant of the
metallurgy involved and suffered the consequences of my