Selectively blackening platinum

Jewelry Discussion
1

Hi There

I have a customer who wants to blacken a pattern that I will carve in
her platinum band ring. The pattern is a rather thin twig design.
Does anyone know how I might “blacken” the recessed twig pattern
only? I know of black rhodium, but I’m not sure if it is possible to
mask the rest of the band to avoid it from being plated. Is this even
possible?

Any suggestions would be greatly greatly appreciated. Thank you in
advance!

Shirley

2 
I have a customer who wants to blacken a pattern that I will carve
in her platinum band ring. The pattern is a rather thin twig
design. Does anyone know how I might "blacken" the recessed twig
pattern only?

There is a technique called Niello. It is an alloy of silver,
copper, lead, and sulphur. The alloy is brittle, so it is prepared as
enamel. The advantages of Niello over the enamel is that after fusing
with base metal, it is very durable. It is so durable in fact that it
is very often used to decorate blades of edged weapons.

Oppi Untracht gives very good description of the process with
several formulas. I can personally vouch for Tula variation.

Leonid Surpin

3

Hi Leonid

Thanks so much for your reply. I’ve heard Niello is quite toxic, but
I will look into it. It’s such a small area I need to blacken, and
something more permanent than plating is very desirable.

I will look into the Tula variation.

Thanks again, Shirley
www.shirleypark.ca

4

Shirley,

I've heard Niello is quite toxic, but I will look into it. It's
such a small area I need to blacken, and something more permanent
than plating is very desirable.

A major ingredient in nielo is lead. Due caution required handling
or grinding it. Normal stuff like a mask, gloves, and cleaning up you
work area… bio-hazard suit and glove box could be optional.

Making the stuff should probably be an out doors exercise (stand
upwind). The last batch I made was indoors with a very good exhaust
system, no problems. The restaurant next door pulled ‘fresh’ air in
about 6 ’ from my exhaust :slight_smile: It was not a good day, fancy talking,
professed ignorance, and luck worked in the end (burning sulphur
really does not smell nice when eating lunch and is a real health
hazard)

Nielo does produce a very nice black inlay, not as durable as the
base metal but not too bad. It does take a bit of practice to get it
right.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

5

Hi Jeff

A major ingredient in nielo is lead. Due caution required handling
or grinding it. Normal stuff like a mask, gloves, and cleaning up
you work area... bio-hazard suit and glove box could be optional. 

Making the stuff should probably be an out doors exercise (stand
upwind).

Thanks for your thoughts. I’ve been doing some reading on the orchid
archives on Niello, and the more I read, the less confidant I feel!
I’m living in Toronto, Canada, and we’ve just got a nice dumping of
snow, so the option of working outdoors is slim right now.

I did read one post that suggested using auto paint as a
safer/healthier/easier alternative. I could suggest that to my
customer, or simply persuade her to honour the natural beauty of
platinum - and not try to alter it.

Thanks again,

Shirley
www.shirleypark.ca

6 
The restaurant next door pulled 'fresh' air in about 6 ' from my
exhaust :-) It was not a good day, fancy talking, professed
ignorance, and luck worked in the end (burning sulphur really does
not smell nice when eating lunch and is a real health hazard)

That reminds me of something. There was a time when I was doing my
own refining. One day, after extracting gold out of solution and
settling silver, I decided to find out if I had any platinum in the
solution. I did not have all the required chemicals, so I decided to
substitute ammonia instead. I like to fancy myself as chemist, which
I am not, and it was one of those days. I got the most weirdest
reaction. The solution seized and became like jello. The worst part
was the smell. It was the worst, I have ever came across, and I have
experience in that area. I flush it down the toilet.

The building I was in, was mostly occupied by jewelers, but right
bellow me there was an accounting firm, and bellow them actually was
a refiner. The vapors that stuff produced were heavier than air, so
my place cleared out quickly, but it settled in the accountants
place, and they are not as hardened against nasty smells as jewelers.
So they start running around the building trying to figure out where
it is coming from. When they knocked on my door, I with the most
innocent look, told them that I am just an engraver and the most
likely source is the refiner bellow them.

Leonid Surpin

7

Shirley,

I did read one post that suggested using auto paint as a
safer/healthier/easier alternative. I could suggest that to my
customer, or simply persuade her to honour the natural beauty of
platinum - and not try to alter it.

Mixing and making the stuff was what nearly got me in bad trouble,
wrong temperatures etc. And I was in Toronto. Working in Vermont now
and similar climate, 10 well planned minutes outside work are not too
bad. Applying the stuff inside not too bad but care is still on
order.

I don’t like paint period, nielo is very pretty but touchy, a copper
flash and liver of sulphur is pretty easy. I like black backgrounds
but they are often difficult. Nothing is as easy as it should be :slight_smile:

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

8

Leonid,

So they start running around the building trying to figure out
where it is coming from. When they knocked on my door, I with the
most innocent look, told them that I am just an engraver and the
most likely source is the refiner bellow them.

We don’t always agree but it is almost scary how we both handled bad
errors with an innocent smile :slight_smile: As I am learning the world is round.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand

9

here’s something from left field… copper plate and LOS then polish
off the highlights. Honestly I don’t even know if this would work

10 
The pattern is a rather thin twig design. Does anyone know how I
might "blacken" the recessed twig pattern only?

You could always inlay the twig pattern with another metal that will
oxidize.

P@