This is probably a stupid question with an obvious answer, but I’d
like to ask it anyway. On a few occasions, I have attempted to
solder gold details onto my sterling jewellery, sometimes with
success and other times not. I haveused both 9k and 14k pieces.
Unfortunately, I have not made a note (mental or otherwise) whether
one works better than the other, and experimenting is too expensive.
The problem is, that when it doesn’t work, the gold actually
disappears intothe sterling silver, but not only that. It actually
seems to eat a hole in the silver too! It’s difficult to describe,
but the last time I tried it, I was soldering small silver balls
onto a silver setting I’d made (faux granulation), but decided to
add some gold ones as a contrast. I noticed that the gold ones were
disappearing into the silver as quickly as they were being soldered.
When I looped it, on the back of the piece, the gold had "eaten"
great big holes in the silver setting!!!
Can anyone explain what is going on, and perhaps what I need to do
to avoid this. I know people use Keum Boo as an alternative method,
but you don’t always want the decoration to be flat and level with
with the surface of the sterling.
Use 65 silver solder and watch very closely to not get it too hot.
What is 65 silver solder? And how would it make a difference? My
solder of choice is a plumb solder from Stuller, which passes the
hallmarking tests. I know there are other UK solders that pass them
too, but I’ve still got lots of my favourite solder left so won’t be
trying them for a while. Would 65 solder pass hallmarking?
Helen, one word: Yellow silver solder! its all about melting points.
the gold will always eat a hole in the silver- because the silver
melts first as it flows at a lower temp and appears to eat a hole in
the metal. Yellow silver solder is the answer. it matches mostly any
gold in 9-14 karats and some occasionally in the 18 lemon yellow -
rich gold colour range. let me know if you can’t get it in the UK. I
have a source (well two) here and will be happy to mail it to you.
rer
Your actual question was what is going on. My understanding of what
happens is, with a little too much heat, the metals form their
eutectic alloy-- the combination of the metals that has the lowest
possible melting point. Since the new, local alloy has a lower
melting point than the surrounding metal, it tends to create a pit
where the metal has alloyed.
I am very familiar with this problem from my own attempts to fuse
gold and silver. With practice and extreme focus, this can be done
very successfully, but it is not easy.
Soldering silver and brass together is particularly likely to
produce collapse, since together they tend to turn into a puddle of
easy solder.
This is not nearly as heartbreaking as when it happens with gold, of
course.
Overheating gold-filled even a little causes the gold to alloy into
the brass-- and you are left with very expensive brass.
If I were going to try to solder granules of gold onto silver, I
think I would do it with plumb gold solder, and preferably by heating
from underneath the silver. Possibly the safest (though not quickest)
way to do it would be to bur or dap a little divot where each granule
was to go, then melt a speck of solder (gold or silver) into the
divot. Add the granule(s) and re-heat, being very careful to stop the
moment the solder flowed.
I had the same problem-- & then I found out that the melting
temperature of 14k gold is about 50 degrees off the flow point of
hard silver solder. I solved it by switching to 18k gold. It’s more
expensive to buy but costs much less in the long run when you don’t
have all of your pieces turning to some kind of weird metallic mush.