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Silver ring coating?


#1

hii took in a ring today for sizing down 4 sizes (uk). it looked like
rhodium plated silver and should have been a straight forward job.
it had a faint 925 punch that looked like it had been cast into the
piece but no other marks.

when i went to saw through the ring the blade just slid over the
surface of the ring (in hindsight this is where i should have said
something’s not right and returned the ring).

i removed the piece but when i bent the shank for the sizing i heard
a cracking - there were lots of little fracture lines on the surface
where it had been bent.

the ring soldered fine with silver solder so i cleaned up, (there
was a copper underplate) polished and plated best possible. im not
charging the customer because im not happy with the job but if they
complain what are my options? -“sorry i messed up your new ring, i
got caught out.” probably not good for business… im a bit
frustrated at both my apparent lack of technical knowledge and being
throw a curve ball that i couldnt fix to the best of my ability. why
would the ring be so heavily rhodium plated? -how do you achieve
such a heavy plate and have it still look good and bright? could it
have been platinum coated silver that ive started seeing in shops?

any thoughts gratefully received!


#2

They call this “rhodium plated” but it acts like nickel plate. When
my blade slides over silver rings as you describe, I do give the ring
back and refuse the job.


#3

Jon,

I have come across this myself while working on a customers new
ring. It probably is not Rhodium plated but another type of heavy
plateing. It does crack and flake when worked on and also the saw
will slide off instead of the teeth actually gripping and cutting as
you discovered.

What I have did in the past when this happened to me was completely
remove the plating after soldering and just polish the ring normally.
Explain to the customer that it was coated and in the sizing process
this could not be avoided.

Next time really look at the ring and or charm. Assess it before you
do the work, hopefully catch it when first taken in. That way the
customer already has a heads up.

I have come across this will charms, earrings and pendants.
Everything seems to be plated. Yes it looks pretty to the customer
but it created a nightmare of us jewelers who are asked to repair
their piece.

Laurie


#4

Hi,

Technically it is not Rhodium plated… because it is too expensive
to do on silver. Normally it should be nickel coated as it is not
easy to mirco plate Rhodium. Jewellers only “flash” plate their
final products with Rhodium solution which is around 25-45 seconds.

Guess it was coated on silver to be more tranish resistance.

As for your job,maybe you can try polishing it before your next step.
In this way you can “see” what is inside of this ring… The other
way is heat the whole ring and you can see “wrinkles” like surface
because the heat apply on the ring “melt” the mirco-plated surface.
By than you can see the exact metal behind this coat Hope this can
help

Stepfan chong


#5

This sounds a lot like a .925 ready-mount ring that I got years ago.
Very shiny, no tarnish after years, hard and brittle. One
manufacturing jeweler that I showed it to thought it might be alloyed
with zinc instead of just copper.

Al Balmer
Pine City, NY


#6
They call this "rhodium plated" but it acts like nickel plate. 

There are some funny things about plating, one of them is that in
certain metals when they are plated align their atoms in a fashion
that results in a super hard highly stressed coating. Platinum group
metals are like this, if you try to put too thick of a layer of them
on the piece the stress will be so great that it will literally peel
off all by itself just to relive the stress. So it is not acting
like nickel it is acting like rhodium. This is problem is further
compounded by the likelihood of a nickel under-plate along with the
copper the OP noted. It is just another reason why plated jewelry
sucks to repair.

James Binnion
James Binnion Metal Arts


#7
I have come across this will charms, earrings and pendants.
Everything seems to be plated. Yes it looks pretty to the customer
but it created a nightmare of us jewelers who are asked to repair
their piece. 

And if we (who work to-the-trade) refuse to work on it, retailers
will stop buying it.


#8
Technically it is not Rhodium plated... because it is too
expensive to do on silver. 

This is not correct. Many silver items are rhodium plated and the
hardness encountered also indicates rhodium vs nickel which
typically plates lower in hardness (200-500 HV) than rhodium
(600-700 HV).

James Binnion
James Binnion Metal Arts


#9
It probably is not Rhodium plated but another type of heavy
plateing. 

It is Rhodium, when plated the deposit is extremely hard. This is due
to the way the atoms align when plated. Bulk rhodium is around 122 HV
but as plated it is 600-700 HV. This hardness puts it in the range of
tool steels. You will find that if you sand or use an abrasive wheel
to remove the Rhodium from the area to be sawn it will be much easier
to work on. The best thing to do is electrostrip the rhodium, but it
will require that there is a nickel underplate for this to work.

James Binnion
James Binnion Metal Arts


#10

Hi,

We are talking about Rhodium Mirco plate… not Flash plate For
your info, china can do three different coating from pure silver to
palladium and rhodium with a fraction of your cost… so the issue
is not whether it is cheap or not but a matter of technical know-how
to achive mirco-rhodium plating

stepfan


#11
...like nickel it is acting like rhodium. This is problem is
further compounded by the likelihood of a nickel under-plate along
with the copper the OP noted. It is just another reason why plated
jewelry sucks to repair. 

The ones I’ve seen had copper under-plate and why would [], who are
churning out mass produced sterling(?) junk, put a heavy
electroplated coating of the most expensive metal on the planet?


#12

Hey Jon

I don’t think the rhodium plating could have caused the ring to
crack. Did you anneal the ring first? I’ve had huge problems with
non-tarnish silver (like argentinium) because I took it for regular
sterling and ended up with cracks.

As for the thick rhodium that’s common enough. I was given a pair of
rings to polish last week and was told they were white gold, but
halfway through my boss popped in and told me to be careful as they
were heavily rhodiumed yellow gold!

Hope I’ve helped a bit. Good luck!


#13
We are talking about Rhodium Mirco plate.... not Flash plate For
your info, china can do three different coating from pure silver
to palladium and rhodium with a fraction of your cost 

Yes because you don’t pay your workers the same wages we pay ours

..... so the issue is not whether it is cheap or not but a matter
of technical know-how to achive mirco-rhodium plating 

The technology all came from the US and Europe, China’s advantage is
simply low wages.

James Binnion
James Binnion Metal Arts


#14

What you have probably run into is chrome plating over copper and is
the devil to work with. The best approach for this junk is to refuse
to work on it. Usually one give away is that the ring is too shiny
and the detail seems to be weak. This stuff has been around for quite
a while and is usually sold mostly by discount stores. The items is
indeed sterling, but the plating will not bend and any metal movement
will result in cracking.


#15

Hi,

You will be suprise china is no longer a source of cheap labour.You
have to see it yourself especially in jewelry line…with so much
hidden cost and if you were to do everything in china with proper
channel, it cost more than you see from the “front” Than from
productivity point of view,it cost more than yours… Normal
Plating is no longer consider as “technlogy”,it just that they are
willing to do it for cheaper return. All three coat plating are out
source. By the way,i am from singapore

stepfan


#16
This hardness puts it in the range of tool steels 

How thick a layer of rhodium are we talking here? We have to rhodium
our white gold, because of the poor colour of many alloys, and it’s
quite common for us to size the ring afterwards to suit the buyer.
I’ve never had any problem sawing it.

Jamie Hall
http://primitive.ganoksin.com


#17
You will be suprise china is no longer a source of cheap labour.
[snip] 

I should not have singled out China. I think you would be surprised
at the cost of manufacturing in the US or Europe. Prices in Asia
have been raising for a long time but it is still much cheaper to
hire labor in Asia than the US or Europe, this is the main advantage.
And with so little regulation (or enforcement of) in most Asian
nations the cost of doing business is cheap. With the exception of
Japan it is still way less expensive to manufacture in Asia and ship
to the US and Europe than to make it here. As long as that is the
case our corporate buyers and manufacturing companies will continue
to outsource manufacturing to Asia.

James Binnion
James Binnion Metal Arts


#18

This hardness puts it in the range of tool steels

How thick a layer of rhodium are we talking here? We have to
rhodium our white gold, because of the poor colour of many alloys,
and it's quite common for us to size the ring afterwards to suit
the buyer. I've never had any problem sawing it. 

The hardness is not affected by the thickness but the degree of
difficulty in cutting through would be. But as someone suggested it
might also be chromium plate. They both plate at similar hardness
but chrome would be much cheaper so it is plausible that it could be
a thicker chrome. But it could also be heavy rhodium plating.
Without analysis it is hard to say.

James Binnion
James Binnion Metal Arts