Why doesn't Mitsubishi make a copper or brass version of PMC?
There are probably a dozen reasons that have to do with the economics (PMC is very expensive to make, so even a copper version would be at least $20 a package), but those issues never get to the table. The nature of base metals prevents them from simple sintering.
    Copper and brass have the ability to take on great colors. They can do this because they are very active at a molecular level--copper is eager to hold hands with oxygen, sulfur, and just about anybody else who passes by. All these reactions translate to the colors we call patinas. But it is exactly this ability that makes copper and copper alloys impossible for PMC.
    The scientists at Mitsubishi were able to create an 18K version of PMC. Depending on the color (they made white, yellow, and pink), this contained as much as 20% copper. It could be fired only in a hydrogen-atmosphere kiln. In fact, it requires a two-step process. First the work is fired in an oxygen atmosphere so the binder can burn away. Then the kiln is sealed and flooded with hydrogen or some other inert gas. It is brought to fusing temperatures here. Higher proportions of copper were not successful, even using this apparatus. Such a kiln costs over $10,000 and can be dangerous to use, so Mitsubishi decided against marketing those versions. I suppose if someone wanted to buy a large quantity they would consider making it to order, but it is not seen as a viable commercial product.

Which version of PMC is the most malleable?
Is it stronger if I fire it longer?
The density of PMC depends on several factors, so a simple "longer is better" answer doesn't quite cover it. If I was forced to give a three-word answer, that's a good one, but not completely accurate. Here are the various factors:

1. First off, metallurgists use a variety of terms to describe the physical condition of a metal: malleability, tensile strength, ductility, wear resistance, brittleness, and density are on the list. The fact that these terms, (and testing devices) exist and are in common use suggest that there is more to this enquiry than meets the eye. For determining the best material for enameling, density is the most appropriate factor to examine, but bear in mind that there are others.


2. Density in metals is just what commonsense would lead you to expect. If, for example, you pick up a handful of damp sand, the grains are touching and pulled together only by the force of gravity. If you squeeze that handful in your clenched fist, the grains will shift around until they fit closely together. The same quantity of sand now takes up less room, it contains fewer spaces between grains, and what spaces there are have become smaller. A strong person can clench tighter than a child, which is to say that the amount of external pressure also affects density. But even with extreme pressure, there is a point where the handful of sand cannot be compacted any more. That is, there is a point of maximum density.


3. Now imagine two kinds of sand. From one beach, we get a coarse, gravelly sand. From the beach they show on the travel poster, we get that fine sand that feels great between your toes. Conduct the same squeeze-the-handful experiment, and you'll find that the fine sand starts out denser, and yields a very dense result when compacted.


4. Now, to take all this into PMCland:

   a) Original PMC is made of a silver particles of mixed sizes. Acceptable density occurs when the material is held at 1650° F for two hours. Extending the time by several additional hours adds very slightly to the density--not enough to register outside the lab. Exceeding the recommended temperature leads to brittleness and risks melting.

   b) PMC+ uses smaller particles, sorted into two sizes. These two factors make the material denser and allow it to be fired for a shorter time. The two sizes provide increased surface contact between the components. The uniformity of size prevents irregularities as the particles line up. Each of the three firing sequences yields the same density (which is significantly greater than Original PMC). Increasing the time may add slightly to the density.... firing at 1650° F for 30 minutes instead of the recommended 10 minutes might add a few percentage points to the density. There is no benefit to going to a higher temperature.

   c) PMC3 is made of still smaller particles. As with PMC+, increasing the time will slightly improve the density, but maximum will be achieved within two hours. There is no reason to exceed 1650° F or two hours. I recommend at least 45 minutes when firing at the lowest temperature (1110° F / 600° C).

Can I make my own syringe style PMC?
In order to make your own version of syringe material you need to thin the PMC with a lot of water. This will squirt out of a nozzle OK, but then the line sags because the material is so diluted. The results are worthless. For this reason the scientists in Japan reformulated a version just for the syringe. It comes pre-loaded and ready to use.