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Wednesday, 7 October 2009

Metal Clay - Introduction

nb: And so, I've been putting off to write about the metal clay course that I've attended. I've actually written quite a long draft for this post but it wasn't saved and I have to redo everything! Bummer! Which I ended up dragging it till today to complete it (I hope I still manage to capture the essence of the first draft)..... and I thought Blogger does the saving thing automatically?? o_O

Before I go on to talk about the course itself in another post, I'll talk about what metal clay is first in this post as I believe the exposure of Malaysian to metal clay is still relatively low. Having been invented only in the early 90s by Mitsubishi Material Corporation under the brand name Precious Metal Clay (PMC), it is afterall still considered as a relatively new medium.

I attended the 2 full days metal clay course a week after the lampworking course. Most of you would probably heard of it as precious metal clay but after coming to a better understanding of it, I think precious metal clay is actually the brand name which has turned into a generic name for silver clay. So, I shall just refer it as silver clay henceforth.

Metal clay is quite an amazing thing, really. In its unfired form, it is soft and you can manipulate it in any way you like just like you would with most clay. The magic happens in the firing process. Once fired, the clay is 'sintered' and it becomes metal in which case you can deal with it in any way you like just like you would with any metal! (I actually did this experiment later on in the beginners' silversmithing class but more on that later) Tell me that's not amazing!

I think the term clay itself is a misnomer because there is nothing 'clay' about it. Metal clay is made up of fine metal particles, water and organic binder. During the firing process, the water and organic binder is burnt off and what is left is metal. I used the word fine metal particles because the resulting metal is fine metal. We're talking about 99.9% pure silver and 22ct fine gold here.

There are at present only 2 companies manufacturing metal clay worldwide and both companies are from Japan. Mitsubishi Materials Corporation was of course the pioneer with PMC, followed by Aida Corporation with Art Clay.

There was some discussion going on between the difference of the two but since PMC itself has gone through substantial changes from it's original formulation, I think you can now safely assume that they are both the same. It's just like cola drink. Whether you like Coca-cola or Pepsi and I reckon why one would choose one over the other depends largely on your first experience with metal clay, in which case one would be more inclined to use one over the other.

My first experience with metal clay was with Art Clay. So, yeah.... I tend to lie towards Art Clay. I've gotta admiy though that I haven't tried PMC before.....or yet to! :P

Anyway, what's interesting is the form in which metal clay comes in. I'm not being biased but since I was introduced to Art Clay first, I'll give a run down on Art Clay's range of products. Although I must say that my instructor was biased towards Art Clay, so I guess it's going to influence me in some ways or other. :P

Anyway, the range of products between the two, PMC and Art Clay are quite similar. Different forms bring about the different techniques involved in working with this art form.

Lump Form

This is the form that most clay come in; lump form. It is malleable as with any other clay and will take any shape and texture. But Art Clay has an interesting formulation. The slow dry formulation.

The slow dry version I find to be much much easier to work with because just like the name suggests, it's slower to dry. You have bo idea what a pain the original version was to work with. It dries up real fast.....and I mean FAST! And what happens is that the clay cracks along the way which is gonna give you a big headache!

But despite this, some people like to use the original version for making rings much better. Difficult for me to explain why but it lies in the technique for ring making. I've yet to try the slow dry version for ring making though since the one we used in class was the original version and I totally hated it!


The name itself is very explanatory. It's in a greyish paste form and what you do is paint layers and layers of the paste on the object you want to emulate. They normally use this with combustable materials so what happens is that the combustible materials burn off during the firing process and what is left is pure silver taking the shape of the object on which it was painted on.

If you can't catch my drift here, it couold perhaps be clearer when in my other post where I show you what I had actually made with the paste.


Erm, yes, it's in a syringe. As simple as that! It's not exactly paste filled into a syringe because the texture is slightly different. I think I can safely assume that it has got a thicker consistency than the paste form. You use it with different sized tips to make 'wormy' looking strands. Heheh.... well, they sure look like worm to me! :P

Maybe 'cream' would be a better analogy? You know like how cake decorators pipe out icing onto the cake? It's something like that...... I think!


Well, you guessed 'em right. It's like paper. Don't ask me how it looks like, feels like or how to work with it because this is a relatively new product (I think!) and we did not have the opportunity to try this in class but the name itself sounds intriguing enough, doesn't it?

Now, the following few is what I believe to be exclusive from Art Clay since I've yet to see them available in PMC range of pruducts but if I should guess correctly, I think it's probably only a matter of time before PMC also comes out with their version? Their formulation is I presume much more complex than the ordinary ones since they seem have 'specific functions'. o_O

Well, anyway......

Slow tarnish formulation

These are available in lump, paste and syringe form and also cost more. Exactly how far a difference it is in its formulation compared to the ordinary ones, I don't know although I do find the term slow tarnish just as appealing as I'm puzzled.... o_O

I haven't tried the slow tarnish formulation but the slow tarnish version I've heard is a new formulation and something which Art Clay comes up with after complaints from the Japanese that the original formulation due to the tarnish issue as a result from the climate in Japan.

To be honest, I find it a bit strange though that this is even an issue. This is 99.9% silver and you wouldn't be expecting silver that pure to tarnish so soon. Technically, it should tarnish much slower than sterling silver which is only 92.5% silver.

Okay, I'll just digress a little to talk about the properties of these metal. Basically sterling silver is only 92.5% silver (which is where you get the .925 number from) and the rest, 7.5% an alloy which is usually copper. The addition of copper makes the metal stronger but at the same time causes it to tarnish in the long run. This is also the reason which you get firescale when you torched sterling silver and need pickle to remove the firescale.

Pure silver on the other hand, has a higher content of silver; 99.9% silver (well, as with most things, there will never claim of 100% .... just in case, you know ;). Pure silver should be much slower to tarnish. And also because of this high silver content, you fused pure silver but you solder sterling silver.

Soldering requires and external factor; a solder, to join the metals together but fusing magically joined the metals together just by heating. That's the difference and it all lies in the copper content.

And because of the abscence of copper content in pure silver, this also makes the metal weaker compared to sterling silver; which is why pure silver is not normally used for making cuff bracelet.

Pure/fine silver is also the whitest metal available and great for those with metal allergies due to the abscense of copper.

Which is why I find it a bit strange that there is even an issue with tarnish. o_O

Anyway, just for experimental sake, I've been wearing a ring I made from silver clay for the past week, since I was back, in our weather and in the habit of most people, i.e sleep, shower, exercise, doing the dishes, doing the house chores and what not with it just to see how the metal survive through it all. And I also have my mum do the same with a sterling silver one which I made in the beginners' silversmithing course.

It's probably too soon to tell but so far, both seem to be doing just fine. We'll see how it is in a few months time.

Oil paste

Basically, the rule of thumb when working with metal clay is that it has to be thick enough and whatever attachment that you want to make has to be made before it is fired.

If it's not thick enough, your pieces will crack during the firing process. One of my pieces actually crack because of this and I'll show it to you in another post.

Also, you can't join fired pieces together.

Silver clay is great for people with zero silversmithing knowledge to make silver jewellery. Therefore, whatever joining work you want to do has to be done pre-firing. Most of the time, you joined pieces together with the silver paste. It's just like what you do with glue. Once fired, it becomes metal and any work on it would definitely require some silversmithing knowledge.

Well, this is where the oil paste comes in. Also one of the newer products. Oill based and meant for post firing work. What oil paste does is to repair cracks (so that your effort is not wasted! Cracked pieces are considered ruined pieces... :P) and join fired pieces together.

Yet to see, feel or work with it and that is all that I can say for now. :P

Overlay paste

This is also a very interesting new product. Imagine it to be like water colour, paint or anything like that. It is in a viscous, liquid form and water soluble. You use them to do drawings on porcelain, ceramic or glass.

After firing at appropriate temperature, the silver powder solidifies and turns to 99.9% pure silver.

Didn't try this also and therefore can't comment much either.

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