I only bring up this subject because it appears to me that the
different versions of precious metal clay are trademarked as
specific products, but the general concept of precious metal clay is
in public domain. Has anybody made their own precious metal clay?
It might be a simple task if you had finely divided silver powder
and a proper binding agent. I remember many years ago in Jr. High
School, the chemistry teacher made finely divided silver by
precipitating it from solution. The solution might have been silver
nitrate. I don’t remember what he added to make it precipitate.
That would leave the binding agent. I read an article about how
beads were made in Africa from powdered glass. They mixed saliva with
the glass powder, rolled it into balls, then placed it inside a
steel can in an open fire. The glass powder sintered together. I
have done this a few times and once when I had a dry mouth, I used
beer as a binding agent.
I would try to make my own precious metal clay, except I don’t know
enough chemistry to make finely divided silver powder. My guess
would be that I could dissolve silver in nitric acid, then when no
more silver will dissolve, I add a less noble metal like copper or
iron.
So, if anybody can tell me how to make finely divided silver powder,
I will try to make precious metal clay using saliva or beer as a
binding agent.
My goal is not to compete with commercially made precious metal
clay. I expect that commercially produced precious metal clay is
superior to anything home made. It would just be fun try to make my
own.
the chemistry teacher made finely divided silver by precipitating
it from solution. The solution might have been silver nitrate. I
don't remember what he added to make it precipitate.
It is copper which is added to make the silver precipitate out of
the silver nitrate.
I only bring up this subject because it appears to me that the
different versions of precious metal clay are trademarked as
specific products, but the general concept of precious metal clay
is in public domain.
There are patents on precious metal clays (see “Moldable mixture for
use in the manufacturing of precious metal articles” 5328775), so it
was not public domain. That particular patent has expired however so
you might try that as a starting point for your experiments.
all one has to do is buy fine silver powder/dust in the micron size
you desire…start there, make a binder of anything moldable from clay
to gum tragacanth and clay ( depending on how slow you want it to dry
dictates the mixture and the clay particle size). Like Binnion said
do a bit of research and you can find some recipes or experiment on
your own…it’s not at all complex… just remeber not to select
sulfur containing binder elements or anything with waxes that are
petroleum/paraffininc oil based or you’ll get not only a product that
doesn’t work or preform like metal clay available commercially but a
lot of smoke too…Ordinary potters clays have too large a particle
size so don’t think you can just take porcelein clayor similar
combine well with powdered silver and burn it off.The ratio of binder
to moisture is different in metal clays that will sinter…rer
It is copper which is added to make the silver precipitate out of
the silver nitrate.
How much?
Shouldn’t really matter… add copper until it till it stops
precipitating. You’ll have a solution of Nitric acid and copper
nitrate with a silver sediment. Filter and neutrilize. It should be
a really basic equation to solve though if you really want to be
finicky about it. Saw a few videos on YouTube about it.
Just put a chunk of copper into the silver nitrate solution, the
larger surface area the better, so a coiled piece of copper wire is
good. Occasionally shake the pure silver particles off to re-expose
the copper surfaces so that the reaction can carry on and away you
go, collecting pure silver in the bottom of the beaker.
Just put a chunk of copper into the silver nitrate solution, the
larger surface area the better, so a coiled piece of copper wire
is good. Occasionally shake the pure silver particles off to
re-expose the copper surfaces so that the reaction can carry on and
away you go, collecting pure silver in the bottom of the beaker.
wouldn’t this approach tend to produce larger silver crystals? For
PMC type products, one would want the silver particles to be quite
small and uniform, not larger crystals. With a solid copper piece,
wouldn’t the silver crystals grow while in contact with that copper?
I’m wondering whether a liquid precipitant of some sort wouldn’t be
better. In refining gold, one can precipitate the gold from a gold
chloride solution with a ferrous sulphate (I think that was it)
solution stirred in. This produces an instant brown cloud of gold
precipitate which slowly settles to the bottom of the vessel, and
when dried, is a very fine powder. I’m thinking some similar method,
with a liquid precipitant, might be preferable. What do you think?
Am I all wet here?
Just put a chunk of copper into the silver nitrate solution, the
larger surface area the better, so a coiled piece of copper wire
is good. Occasionally shake the pure silver particles off to
re-expose the copper surfaces so that the reaction can carry on and
away you go, collecting pure silver in the bottom of the beaker.
Any school or workshop that teaches etching will plenty of these
silver particles.
First method seems appropriate. If finer crystals are required, a
liquid addition could be ther answer… but as to what would do it,
I’m not sure… and the by products may not be worth dealing with.
...wouldn't this approach tend to produce larger silver crystals?
For PMC type products, one would want the silver particles to be
quite small and uniform, not larger crystals.
The [silver] metal particles need to be very small (we are talking
microns in size), which requires special equipment. Particle size and
shape are essential to making a successful metal clay; these will
determine what firing schedules will work and if you metal will
sinter at all. Binders are typically methyl cellulose (did I spell
that right?) and water with a secret sauce (glycerine, oil, or other
organic plasticizer). As binders are “proprietary,” each company has
their own preferred secret sauce. The materials science aspect of it
is fascinating, but the cost of developing and making your own will
far exceed the cost of buying a few packages if your goal is just to
try it out.
Mary Ellin D’Agostino, PhD medacreations.com
Senior Teacher, PMC Connection
A simplified way to get a very fine crystal of fine silver is to
attach the negative lead from a rectifier to a stainless pan
containing silver nitrate/distilled water. Suspend a piece of fine
silver attached to the positive lead so the silver is immersed and
whatever is holding it is insulated.
To retrieve the crystals, filter the liquid. Let the stainless pan
dry and scrape the sides with a small metal spatula (enameling
supply).
This is essentially what I do all the time to electro-etch fine
silver before enameling it. The crystal powder I retrieve is very
fine and consistent in texture.
You may well have a point about the particle sizes of the silver
collected via the method using solid copper. I’m not aware of the
particle sizes needed for precious metal clay, however.
I did find the following link to a useful looking paper though:
I’m going to print it out and read it when I have time, but it looks
to have some useful suggestions.
Helen
UK
Scratch the line in my other post regarding printing out the info in
the link I found. A) you can’t print it, and B) even if you wanted
to, it’s a book with hundreds of pages!!! But there’s some
interesting info in chapter 20 “Production of Noble Metal Powders”.
I agree about partical size being critical in making one’s own metal
clays however what is not quite true regards the cost of buying
manufactured metal clay from PMC or art clay world on the US
market…it is quite inexpensive to buy graded .999 silver dust and
in a wide range of partical sizes ( usually intended/sold for
industrial use to wholesale eligible buyers)- in fact less than the
spot market for silver since the prices listed ( on most sites where
it is available) are not updated daily, or even weekly in many
instances from all the sellers I have experience with. For the cost
of a 30 gram package from PMC vendors I can make at least 100 grams
of the stuff…for the cost of 1 package of 22 kt gold metal clay (PMC
brand) I can make over 9 grams of 24 karat metal clay…its all in the
sourcing of the raw materials…the actual "admixture is easy to get
right -particularly if you have used manuf. metal clay and have
something to base what you are after on- while starting blind- would
be more difficult, Making ones own paper type is perhaps the hardest
of the forms to do without at least a pasta making machine that has
very good roller tension adjustments/controls on it…That is perhaps
the only thing I would advise against trying as it is easier just to
fork over whatever the price is for that form…all the others,
easy!..rer
You might use aluminum (as in foil) which is cheaper and easier than
copper. The amount to add depends kupon how much precious lmetal you
have to precipitate. The aluminum (or copper) is more reactive than
the silver and will “scavenge” the ions that are keeping the silver
in solution so that it precipitates. All I can say as to quantity of
Al is that you should use an excess (more than there is silver in
solution.
it is quite inexpensive to buy graded .999 silver dust and in a
wide range of partical sizes ( usually intended/sold for industrial
use to wholesale eligible buyers)- in fact less than the spot
market for silver since the prices listed ( on most sites where it
is available) are not updated daily, or even weekly in many
instances from all the sellers I have experience with.
You obviously have never bought atomized (powdered) silver or likely
any other metal form such a vendor. I have and I currently have a
kilo of atomized sterling silver in my safe. The vendor kindly used
my metal which allowed me to pay only the processing charge for the
atomization process and not their charges for the silver which would
have been much higher than what I can buy it for. I have purchased
quite a bit of powdered metals in various alloys and they all cost
more than the same weight of wrought bulk metal. I guarantee they are
just as aware of if not more so than we are as to what the current
spot market for the metals they sell is. Once again you need to do
your homework.
...what is not quite true regards the cost of buying manufactured
metal clay from PMC or art clay world on the US market..it is
quite inexpensive to buy graded .999 silver dust and in a wide range
of partical sizes...
That is true if you are going to manufacture and use a lot of it,
but if you are just doing it out of curiosity or for a low level
hobby, it is a different matter. However, in the process of figuring
out your binder recipe, the particle size you need, appropriate
firing schedule, etc. you will need to spend a lot of time and money
experimenting. The actual cost of the silver powder is only a small
part of the equation.
Mary Ellin D’Agostino, PhD medacreations.com
Senior Teacher, PMC Connection