Had a BIG problem with an 18K rose gold ring. We cast it ourselves,
using David Fell 24K and David Fell 14K rose alloy, but only alloyed
to 18K. Used all fresh gold, no button or scrap. Cast at 900 degrees.
Set some pave’, soldered a head, put the ring in the pickle pot while
still hot from soldering but not red hot(we have to walk to the back
room to get to the pickle pot, so there was at least 30 seconds to a
minute cooling time). When the jeweler pulled the ring out of the
pickle, it had shattered. Huge big cracks running through the entire
ring, the surface looked like a broken window pane! Obviously, we
cannot delliver the ring in this condition, and we need to remake it,
it is a wedding ring, exactly what the bride dreams of,so we need to
know where we went wrong before we start again. Has anyone run across
this problem? Help!
To be honnest with you,I don’t have a direct answer related to your
problem.the only fact i can come up with is that pink gold has lots
of copper in its alloy.When you finished your casting,did it look
redish?Could be that in this case the copperoxide are playing a tirdy
game with you,but I’ve never seen shanks cracked the way you
discribed it. what I don’t really understand is the fact that you
start with pure gold and adding 14 Kt pink gold to it to get a 18 kt
golden alloy,instead of adding pure metals to your pure gold and
decreasing your gold karat? However,I’m sorry that I’m not able to
tell you what’s going on. Hope that a fellow orchid member can give
you a fair explanation for this strange event. Regards Pedro Palonso@t-online.de
Pink gold is easy to alloy it is only copper and silver, it works
very well and can be remelted over and over with out much trouble.
You would have to look at the 14 alloy but I can’t understand why you
would use it with 18ct it takes so little extra metal.
So forget the 14 alloy and do it yourself
A casting temp of 900 is much to low you need at least 1000 to 1100
for copper alloys ,also make sure that the metal is not oxidized in
the melt (oxides have a lower melting point) as this can go into
solution ,use plenty of flux or a small piece of aluminium (0.1 of a
gram)just before you pour.Also before you quench the can it must be
down to 400 or less ,rose gold is very hot short. We have found it
best to make up rose alloys from 24ct making sure they contain some
silver. Hope this is some help,casting is a craft not a science
Marggi, I ran into a similar situation like this a year or so ago. I
had run out of my regular 18 karat alloys and was in a pinch to get a
ring cast for a customer. So, I ended up using some high fluidity
yellow alloys that were designed for 14 karat gold and I alloyed it to
18k instead. The ring looked great after casting, but when I put it on
the ring mandrel to straighten it out, it crumbled into several
chunks. My casting procedure was the same as it had always been so I
called United PMR (source of the alloys) and asked them what the
problem could be. They told me that the two alloys are totally
different and the alloys designed for 14 karat should not be used to
make 18 karat. It seems the 14 karat alloys have a deoxidizer in them
that wreaks havoc on the higher karat gold’s. I don’t know if your
rose alloy has this in it, but it may be worth checking out. Hard
lesson learned…I lost 5 or 6 hours on that job re-carving a new
wax. Now I keep separate alloys for rolling and casting and for each
karat and color. Ken Sanders
That’s terrible, it seams to me that the basic casted ring has had a
brittle matrix with big crystals.
You can have made two mistakes. The gold alloy was overheated and
oxidized before poring . Some of the copper in the gold has become
copper oxide and moved to the crystal edges of your alloy. this gives
a brittle alloy. If you throw this hot into pickle the copper oxide
will solve so fast that there will be high internal tensions on
crystal level. This gives the cracked surface, direct or later on.
To prevent this happening use an reduced flame when you are using gas
and oxygen.( an overdose of gas). and use and anti oxidant as some
charcoal in the melt and cover it with some borax. Also some sugar can
be used, contains a lot of carbon and sticks good to the surface. And
keep the flame always covering the gold surface during casting work…
You can use the gold again but stir it when liquid(egg face) covered
with an borax sugar mixture. so that the oxide gets out.
The second thing what could happened is, when soldering and the
material is heated for a long period, there will be a crystal grow.
Also when you overheat the object during soldering without protection
against oxygen , this will help the copper oxides creeping in. And if
you are using an oxidizing flame you ask for it.
So it seams to me that the copper oxides have solved in the pickle,
and left no binding over between the gold/copper crystals. And if there
are internal tensions in the ring it will crack.
Good luck in doing at again. (And as you know, the second time always
goes faster)
Hello Marggi: I’m sure that you will get an adequate answer to your
problem. I have not had that problem before but here is my question,
You say you set stones and then quenched the piece with (I assume)
diamonds set in it. This is not such a good idea if the stones have
any inclusions that may expand and contract with heat differently.
This can extend fractures and inclusions. If you did not get a good
mix of the alloy and gold before the casting then maybe it can cause
brittleness of the gold and it cracked along the grain lines.
Dear Margi, If you are talking about 18K rose gold (I missed the
start of this thread) It will always be extremely brittle. The
molecular lattice of copper and gold in an 18k configuration is the
culprit. You can have a perfect casting but the molecules all line up
to make a brittle situation. The solution I use is to alloy it to 20K
and charge a little more or just do it in 14k. John, J.A.Henkel
Co.,Inc. Moldmaking Casting & Finishing
The 18k rose gold made with only copper as the alloy can be a big
problem if it is not rapidly quenched after heating. It has to do with
the fact that the 75%weigtht gold 25% weight copper forms a ordered
rather than a disordered atomic latice this makes it hard and brittle.
If it is quenched from high enough temprature it will remain in the
disordered state but if it is allowed to cool slowly the ordered
structure forms and disaster is just around the corner. Most 18k red
alloys have a little silver or other metal addtions to reduce the
likelyhood of this happening but it is not as strong a red color. If
you are working with 18k red gold you really must quench it rapidly or
this will be a continuing problem. In 14k you can get away wuth a
copper gold binary alloy and it will not have as many problems but it
is still better to quench it.
Marggi,We have had that exact problem. The 18k rose is much more
trouble than the 14k rose. We remade the ring in 18k peach from
Hoover. The 18k rose that had shattered was from Stuller. We called
and the tech dept. said that it is their “worst product”, I thought
that was funny. That they have tried to correct it but have been
unable to due to the high copper content. The remedy is to quench
when very hot. But I just won’t make anything out of 18k rose gold
for people, we use 14k rose. If they insist on 18k we use the peach,
it is very close to the rose gold color but much easier to work with,
they usually don’t care that much. I personally think that rose gold
is too red anyway, and that the peach has a more pleasing subtle
color, but that’s just me. Mark
Thanks to all who responded. We were able to recast the ring in 14K
and deliver it on time for the wedding. And to those who rightly
pointed out that we should not have quenched the ring in the first
place-the jeweler who was working on the piece did not intend to
quench it, he was under deadline pressure and made a mistake. When he
heard that sssss when he dropped the ring in the acid, his initial
worry was for the integrity of his pave work, only to pull the ring
out of the acid and discover that the whole piece was in ruins! I
had to include that detail, even if it embarassed of our fine,
talented, but overworked jeweler. No one had any idea that 18K rose
needed such special handling! This list, and it’s members who are
willing to share knowledge and experience, pulled our hineys out of
the fire!