# Silver Metal Clay (PMC)



## 4metals (Feb 29, 2012)

There is a growing market out there for silver (gold too) metal clay. It is made from pure silver power which is very small in size (atomized) and an organic binder. it can be modeled like clay, dried, and fired to make jewelry or whatever. 

Does anyone have any idea what the organic binder used to make the clay is?


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## Lou (Feb 29, 2012)

Usually a mineral oil.


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## 4metals (Feb 29, 2012)

I know that the gold and silver inks used in the heyday of thick film hybrid manufacturing for silk screening circuits was just metal powder and pine oil. I didn't think it would be that simple.

I think I'll try and do it with pine oil for starters.


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## Lou (Feb 29, 2012)

They use rosemary oil and other aromatic heavy oils for the paint on gold and platinum that Degussa used to make.


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## MysticColby (Feb 29, 2012)

hmmmm - one common thing to PMC I've seen is that it's wet - you have to dry it before firing. I wouldn't wet too well if it were an oil?


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## 4metals (Feb 29, 2012)

I've heard it's something like methyl cellulose, which can be wet. The air drying takes care of the water and the firing takes care of the binder.


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## butcher (Feb 29, 2012)

Maybe a product MSDS will reveal a secret.
Or patent search.
I have also read old books of facts and formulas that had similar recipes of how they used to make things.


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## 4metals (Feb 29, 2012)

I got the methyl cellulose fact from a patent but it was vague in percentages and specifics. I don't blame them they get quite a premium for this stuff so they keep the formula secret. 

It is really neat stuff, you mold it like modeling clay, plan ahead for the shrinkage, and dry it and fire it and you have a piece of jewelry. I'm sure there's more to it than that but it seems to be a valuable asset to a manufacturing jeweler. And a good way to get a premium on your silver.


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## Westerngs (Feb 29, 2012)

I know that a company called Rio Grande Jewelers Supply markets the stuff. I will see if I can get any information on the composition, but it is likely a trade secret and not available to the general public.


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## MysticColby (Mar 1, 2012)

My aunt started working with this a couple months ago. She's made a lot of flat pieces with designs on one side. From what I can tell, it doesn't work too well for 3D sculptures. or can it?

where do they get silver powder? cemented from copper? ^_^


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## Smack (Mar 1, 2012)

Westerngs said:


> I know that a company called Rio Grande Jewelers Supply markets the stuff. I will see if I can get any information on the composition, but it is likely a trade secret and not available to the general public.



You could send a sample in to your state lab for analysis.


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## jimdoc (Mar 1, 2012)

Conductive ink may be another product you could make with silver;

http://hackaday.com/2012/02/24/diy-conductive-ink-lets-you-freehand-circuits-on-the-cheap/

http://jordanbunker.com/archives/41

Jim


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## goldsilverpro (Mar 1, 2012)

4metals - I also looked for the binder awhile back and I'm thinking I found some patents. Maybe I kept a file - I'll look and also check my bookmarks.


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## Westerngs (Mar 1, 2012)

Patent for PMC

There is disclosed a precious metal article which is formed of a solid-phase sintered product of a precious metal powder. For manufacturing the precious metal article, a moldable mixture which contains a precious metal powder and a binder removable by sintering is shaped into a prescribed molded object, and the molded object is then subjected to sintering. The moldable mixture is produced by preparing a precious metal powder, preparing a jellylike cellulose binder by blending a cellulose with water and leaving for a prescribed period of time, and blending the precious metal powder and the jellylike cellulose binder together. The most preferable moldable mixture contains 50 to 90% by weight of precious metal powder, 0.8 to 8% by weight of water-soluble cellulose binder, 0.08 to 3% by weight of a surface-active agent. 0.1 to 3% by weight of oil, balance water and unavoidable impurities. The precious metal powder preferably contains gold powder and powder of an alloy containing silver or copper, and the gold powder is obtained by submerged-reduction method.

a) Precious metal powder:

Powders of precious metal such as gold, silver, copper, platinum and their alloys are main constituents for the moldable material to be obtained. If the content is less than 50% by weight, desired effects cannot be obtained. On the other hand, if the content exceeds 90% by weight, the resulting moldable material is inferior in extensibility and strength. Therefore, the content of the precious metal powder has been determined so as to range from 50 to 90% by weight.

In addition, if the average particle size of the precious metal powder exceeds 200 μm, the extensibility and strength are deteriorated. Therefore, it is preferable that the average particle size of the precious metal powder is no greater than 200 μm.

(b) Water-soluble cellulose binder:

When heated, the water soluble binder is quickly gelled, so that it is very easy to keep the shape of the molded article. However, if the binder content is less than 0.8% by weight, such an advantage cannot be obtained. On the other hand, if the content exceeds 8% by weight, fluidity is unduly increased, so that it becomes difficult to mold the mixture. Therefore, the content of the cellulose binder is determined so as to range from 0.8 to 8% by weight.

In the foregoing, methyl cellulose and/or ethyl cellulose are favorably used as the water-soluble binder of the above kind.

(c) Surface-active agent:

A surface-active agent breaks solid substances which are formed by the reaction of the binder with water, and facilitates an efficient mixing of the precious metal powder with the binder. However, if its content is less than 0.03% by weight, desired effects cannot be obtained. On the other hand, if the content exceeds 3% by weight, the fluidity of the moldable mixture is unduly reduced, so that molding operation cannot be smoothly carried out. Accordingly, the content of the surface-active agent to be added is determined so as to range from 0.03 to 3% by weight. As described above, polysoap or alkyl benzene sodium sulfonate is preferable as this agent.

(d) Adhesion-preventing agent:

When a small amount of adhesion-preventing agent, or oil and fat, is added, the moldable mixture is prevented from sticking to hand during the molding operation. However, if the content is less than 0.1% by weight, the effects cannot be obtained. On the other hand, if the content exceeds 3% by weight, the moldable mixture becomes oily and slippery, resulting in poor handling characteristics. Therefore, the content of the adhesion-preventing agent is determined so as to range from 0.1 to 3% by weight.

This agent may include higher organic acid such as phthalic acid, higher organic ester such as di-n-octyl phthalate or di-n-butyl phthalate, higher alcohol, higher polyhydric alcohol such as polyvinyl alcohol, polyethylene glycol, and higher ether.

Furthermore, it has been found that when ethylene glycol is added in an amount of no greater than 30% by weight, preferably 2 to 10% by weight, with respect to water, the moldability of the resulting mixture can be further improved. However, if the content exceeds 30% by weight, the viscosity is reduced, so that the moldability deteriorates instead.

Patent #5328775 

Found it here:http://bbs.homeshopmachinist.net/showthread.php?t=41842


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## goldsilverpro (Mar 1, 2012)

I did keep a patent file. Here's the numbers. The last 3 are patent applications. Some are more applicable than others.
5328775
5702501
6383248
6572670
7081149
7387762
20050241438
20070000351
20110064937

Search for the numbers here:
http://www.google.com/ptshp?hl=&sourceid=navclient-ff


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## 4metals (Mar 1, 2012)

This thread is a great example of refiners helping refiners.

This forum is truly unique.

Thanks for all the input.


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## garage chemist (Mar 3, 2012)

Could someone maybe put a bit of this silver clay into a solvent that dissolves the organic materials, filter out the silver powder and determine the particle size and shape under a microscope? I wonder how they make this silver powder, and I think that a big part of the secret behind making this clay lies in the preparation of the powder. A powder that sinters to form a massive silver artifact far below the melting point has to very fine I would think. 
I think of the possible applications for making silver labware from this clay. I have a little silver crucible and it is great for doing caustic alkali melts.


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## nickvc (Mar 3, 2012)

The silver is melted and poured with high pressure water jets fired at it, I think it was 4metals that posted about it so he has no problems with the silver it's the binder that's unknown.


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## 4metals (Mar 3, 2012)

The secret may be behind the production of the powder but I would also try dissolving some fine silver and filtering it and dropping it as a chloride and reducing it with Karo. This makes a fine clay like mud and with the right binder it may be just a question of adding the binder to your reduced chlorides. 

My interest in this material is that it would be a good and easy way if reduced chlorides could produce a workable product, for our members to get an added value on their silver to sell to local jewelers.


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## Westerngs (Mar 3, 2012)

You might get better powder if you precipitate it with sodium formate. The drawback here is that not all the silver gets precipitated out unless you use a huge excess of reagent.

The powder produced however can range from the 10 micron to the 500 micron range. You just tweak the process a little to make the size you need.


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## 4metals (Mar 4, 2012)

My experience with the sodium formate was a coarse silver crystal, quick to settle. The silver chloride conversion yielded a fluffier less coarse silver.

Truth is atomization does give the particle size needed but takes the process out of the hands of most small guys, that is why I would try a reduction of silver nitrate first.


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## Westerngs (Mar 4, 2012)

The sodium formate method requires some tweaking to get the particle size you want. The more concentrated the silver nitrate and sodium formate solutions, the more coarse and grainier the precipitate produced. Also, the addition rate is important.

I have much experience with both the formate and silver chloride methods. For my taste, I prefer the formate method to produce powders, but the silver chloride method works as well.


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## 4metals (Mar 4, 2012)

I have only used the formate method to drop silver from sterling and the sterling was digested at the rate of 1 gallon nitric, and 1 gallon distilled water per 100 oz of sterling. That is why my experience drops coarse silver. 

Waste treatment problems with in the small shop have steered me away from the process.


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## butcher (Mar 6, 2012)

Here is a thought, also search for information on paste solders, like bismuth and silver pastes, or how they make these solder pastes, maybe not just a search for the silver and bismuth type solder but any type of these, many of these solders you can solder with a match and paste smeared on the wire.



http://www.google.com/#hl=en&gs_nf=1&cp=25&gs_id=35&xhr=t&q=bismuth+and+silver+paste++solder&pq=bismuth+and+silver+liquid+solder&pf=p&sclient=psy-ab&rlz=1R2RNQN_enUS457&source=hp&pbx=1&oq=bismuth+and+silver+paste++solder&aq=f&aqi=&aql=&gs_sm=&gs_upl=&gs_l=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=ebc05c09906f4efd&biw=1024&bih=587


http://www.solder-it.com/manuals/sp7msds.pdf

Another paste solder uses besides metals Diethylene Glycol Dibutyl Ether

http://www.google.com/#pq=bismuth+and+silver+paste++solder&hl=en&gs_nf=1&cp=27&gs_id=p&xhr=t&q=silver+paste++solder+patent&pf=p&sclient=psy-ab&rlz=1R2RNQN_enUS457&source=hp&pbx=1&oq=silver+paste++solder+patent&aq=f&aqi=&aql=&gs_sm=&gs_upl=&gs_l=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=ebc05c09906f4efd&biw=1024&bih=587


Interesting solder
http://en.wikipedia.org/wiki/Solder

http://www.google.com/search?q=paste++silver+solder&btnG=Search+Patents&tbm=pts&tbo=1&hl=en#sclient=psy-ab&hl=en&tbo=1&tbm=pts&source=hp&q=paste++silver+solder&pbx=1&oq=paste++silver+solder&aq=f&aqi=&aql=&gs_sm=12&gs_upl=0l0l0l66734l0l0l0l0l0l0l0l0ll0l0&gs_l=serp.12...0l0l0l66734l0l0l0l0l0l0l0l0ll0l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=300ee25df671c11e&biw=1024&bih=587


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## turtlesteve (Mar 6, 2012)

Isn't precious metal clay still under patent protection? I was under the impression this is why it's so expensive to jewelers, as it would otherwise be easy to make. If so, even if you could duplicate it, it wouldn't be legal to sell/exchange.

That being said, my concern is primarily with the particle morphology. Atomization is ideal because the particles produced are small, dense spheres. This lends well to dispersing the powder at a high solids loading (which is important to minimize shrinkage) and directly aids the sintering (firing) process. Precipitated powders will probably not be spherical - at worst, they could be acicular (needle-like) or porous. These will not be well suited for sintering. 

I have another thought though. Once when I was less experienced in melting metals, I overheated silver to the point of vaporizing it. I found later that the desk I used was covered in tiny silver spheres where the vapors had condensed and settled out of the air. It might be possible to produce a good powder in this way, if you can devise a way to collect the spheres. Maybe you could use a vacuum with a piece of filter paper?

Hope all of this is helpful
-Steve


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## Westerngs (Mar 6, 2012)

As with all patents, you cannot just copy the invention. But if you can find a way to deviate from it and still make it work, then that is not covered by the patent.

For example, the PMC patent gives silver ranges of 50-90% if I remember correctly. If you could find a way to make it work with say 95% silver, then the patent would not be infringed.


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## NobleMetalWorks (Jun 29, 2012)

I posted another thread before I was directed to this one. Has anyone found out anything new on this thread subject?

Scott


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## NobleMetalWorks (Jun 29, 2012)

I found this:



> A new binder system consisting of cellulose acetate butyrate (CAB) and poly(ethylene glycol) (PEG) with various molecular weights was introduced. CAB and PEGs with various molecular weights had good compatibility. The blends exhibited low enough viscosity to make homogeneous feedstock for the injection molding. Shape maintenance during the extraction by an environmentally favored solvent of water was excellent, and final sintered parts had excellent dimensional stability (+/-0.3%) and high sintered density over 98%. We also found that injection cycle time was comparable to that of commonly used wax-based feedstock. (C) 2001 Kluwer Academic Publishers.



Here:

http://www.mendeley.com/research/wa...hylene-glycol-blend-powder-injection-molding/

Is the post talking about the same binder that the patent is talking about? Or is this something different?

Scott


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## NobleMetalWorks (Jun 29, 2012)

I was also looking at different binders, I am thinking about calling this company tomorrow and picking their brain to see if they have anything similar that will do the job as well, if not better than what the patent posted is using.

http://dowwolff.custhelp.com/app/an...excipients-in-granulation-binder-applications

Scott


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## NobleMetalWorks (Jun 29, 2012)

I think I am going to try this recipe first, I thought I would post it here for others to try as well.



> Silver Powder
> -particulate shape appears to work better in as spherical form, although flakes work as well. Particulate size should be less than 8 microns.
> -powder is cost effective to purchase in 1kg increments (price drops to about $.60 per gram or less)
> 
> ...



If anyone has tried this recipe, or one similar, please post your experiences.

Is there a method better than most for producing spheres of silver small enough to comply with this recipe?

Scott


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## NobleMetalWorks (Jun 29, 2012)

A question for anyone who has any experience with the PMCs.

I am interested in making sterling silver and I am wondering if I can use the same recipe above for copper, then mix the correct amounts allowing for shrinkage of copper/silver clays, so that when fired, the end result could rightfully be hallmarked as sterling silver?

Scott


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## NobleMetalWorks (Jun 29, 2012)

I think I'm also going to try rice starch as a binder, it seems like it would behave similar as the Japanese PMCs, and I imagine it very well might be what is used in theirs considering how widely used rice starch is, in Japan. 

Anyone have experience with rice starch as a binder? :mrgreen:


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## nickvc (Jun 29, 2012)

Scott in reply to your earlier question about adding copper powder to the mix the only problem I can see is oxidisation of the copper which might cause problems with the final product, I'm also unsure how your going to get copper powder fine enough to use.


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## NobleMetalWorks (Jun 29, 2012)

nickvc said:


> Scott in reply to your earlier question about adding copper powder to the mix the only problem I can see is oxidisation of the copper which might cause problems with the final product, I'm also unsure how your going to get copper powder fine enough to use.



Oxidation would be a problem, it could only work I think if it was made, hydrated, used immediately or made, hydrated, foil vacuum packaged for later use. I also suspect unless you are replacing with some inert gas, the clay would have a specific lifespan before it became unworkable.

I'm fascinated by the prospect, it seems it would work for other metal alloys as well, perhaps the key is in making each individual clay, and then the buyer mixing them accordingly, at the time of use.

Scott


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## Emporio (Oct 24, 2013)

NobleMetalWorks said:


> nickvc said:
> 
> 
> > Scott in reply to your earlier question about adding copper powder to the mix the only problem I can see is oxidisation of the copper which might cause problems with the final product, I'm also unsure how your going to get copper powder fine enough to use.
> ...



Scott, I'm interested to know how it went out for you. Did you use that recipe you posted?


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## solar_plasma (Oct 24, 2013)

If I hadn't too many projects running I would try to make colloidal gold (cassius') and colloidal silver (thread about electrolysis of silver in plain water). I would try to obtain a blend of gold and silver equal to a only-gold-silver alloy for jewelry, something like 75/25. Then vaporise the water in a desiccator, if other methods of vaporizing would cause loss of PMs or use a centrifuge. When most of the water is vaporized, I would add the binder, - methyl cellulose sounds nice...wallpaper adhesive :lol: 
Then I would go on vaporizing until the material has a kneadable consistency.

Just my unworthy thoughts...

edit: cassius' wouldn't work, the gold is blended with/bound to SnO2 :roll: could it be dissolved without getting the gold to coagulate?


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## solar_plasma (Oct 24, 2013)

> edit: cassius' wouldn't work,



maybe this book gives an answer, how make proper colloidal gold (Lehrbuch der anorganischen Chemie, Hollemann/Wiberg):
http://books.google.de/books?id=eGk...e&q=Lehrbuch der anorganischen Chemie&f=false

page: 1359 and 1363

I am not sure but I guess methylene chloride (cas nr. 75-09-2) is nothing for the hobbyist, probably cancerogen, unhealthy like all those nasty chlorinated hydrocarbons and capable of certain nasty reactions. On the other side it is or has been contained in common solvents. .....Au55(PPh3)12Cl6 :?: :?: :?: :lol: looks like swahili to me


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## solar_plasma (Oct 25, 2013)

Sorry, here is the link to the english version, - nice read also to us halfeducated non-scientists:

http://books.google.de/books?id=Mtt...AEwAw#v=onepage&q=INORGANIC CHEMISTRY&f=false


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## butcher (Oct 25, 2013)

after going through to book to glean some good information It was disappointing, Somebody took out the pages with precious metals from that book.


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## Palladium (Dec 31, 2014)

I now own silvermetalclay.com ! :mrgreen:


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## 4metals (Aug 16, 2018)

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## Owltech (Aug 16, 2018)

4metals said:


> There is a growing market out there for silver (gold too) metal clay. It is made from pure silver power which is very small in size (atomized) and an organic binder. it can be modeled like clay, dried, and fired to make jewelry or whatever.
> 
> Does anyone have any idea what the organic binder used to make the clay is?



I had mixed results with flour or chewing gum as binders, and good results with wallpaper glue (methylcellulose)


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## Palladium (Aug 16, 2018)

MEC is good. Regular Elmer's school glue will work! Use only what you need. It's PVA and will burn away.
Add just a drop of Glycerin to keep it from drying out to quick while you work it. It also helps with any oxidation if you're doing sterling mixes.


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## Lou (Aug 16, 2018)

Apparently a lot of stuff in these.

The stuff I would see painted onto glass or ceramic surfaces that was Au/Pt based were more piney smelling.

The PMCs seem to be mixtures of carboxymethylcellulose, butylated celluloses, polyvinyl alcohols etc.

One of our customers make a paste for brazing that is basically that.

Anyway, Ralph, have you ever tried to take the formate silver product, dry it real well, and use that for making these pastes?

I think something like a small sand muller type deal would work really well for getting the material really bound well.

http://mifco.com/sand-mulling-equipment/batch-mullers/


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## Palladium (Aug 16, 2018)

When i first started i tried silver from the formate reduction, but it was to course and that lead to shrinkage issues. The best tick i found was silver nitrate reduction with NaOh to silver oxide. It's a fine powder that washes well and after washing you can put it in a regular oven to dry it and convert it to metallic silver. Then mix with your choice of bonding polymers.


[youtube]http://www.youtube.com/watch?v=10HoroBaXUI[/youtube]


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## snoman701 (Aug 17, 2018)

You may also try converted silver chloride. 

Or even your Naoh added to silver nitrate under high shear. The shape of the silver particles will be very important for the workability. Traditional clay is often arranged in sheet like particles, held together by electromotive forces. These create a certain "springiness" to the clay...but most of all, it's how the clay stays together once dried.

Also, a mixture of particle sizes helps influence workability. It's like building a gravel driveway....the particles lock together.

On a small scale, mixing clay is difficult. I've mixed pottery clay in everything from gram size lots to 1000 lb lots....it's hard to get the same plasticity you get in a large paddle mixer on small lots. There is a gentleman named Paul soldner. He built a pilot size mixer for studio potters to recycle their clay, and make custom blends.

If I were trying to do this on precious metal pilot size batches, I'd use a kitchenaid mixer but make a plaster or concrete bowl. You start with a clay slip with extra water, then add small amounts of dry materials to get it closer to a workable stage. Then just stop and let it mix. The porous bowl will continue to wick water from the clay, giving a uniform product....past the point where you could add dry material and get a uniform mix.

After removal from the bowl, placing your ball of clay on to a similar porous slab will help bring it to a perfect workable point. You just pick up the ball occasionally and wedge it (process of working clay by hand).

The most important aspect of making a workable clay was the use of recycled aged slip. It was loaded with bacteria. The chemical transformation from the bacteria had great influence on the workability of the final product. Some porcelains are almost unworkable without an aging period.


Sent from my iPhone using Tapatalk


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## Palladium (Aug 17, 2018)

That's exactly how i made mine. Except i made a semi wet slurry and instead of adding dry powder i evaporated it down until i got the right moisture content by test with a meter. I used a dough mixer.
I put the clay between two wax sheets of paper and rolled it out. Then take an exact o knife and cut out squares.

I though about using a cookie cutter and stamping some out! :lol: :lol: :lol:


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## Drdixiecup (May 24, 2019)

I’m a metal clay user. Things important to me are the working character and shrinkage rate. Workability is better with a little stickier clay. I roll small coils and shape them. Some processes are much better in a low shrinkage clay - like setting faceted stones or embedding wire or other metal pieces. 

I’d be happy to test your trials if you want to send some.

I was interested to see a fine silver/ palladium combination which should add strength and hardness while preserving the bright white luster.

Bill Struve was known to me, he marketed his proprietary brands of metal clay and was a great resource.


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## FrugalRefiner (May 24, 2019)

Welcome to the forum!

Can you provide any insight into the make up of the clays, e.g., binders used, percentages, etc.? It's a subject that has always interested me, but there aren't a lot of details available.

Dave


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