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About Precious Metal Clay (PMC)
Comparison of PMC3, PMC+ and PMC Standard-type
The following are the physical properties and characteristics of each product:
Name (in Japan) PMC3 PMC Quick PMC Standard
Name (in the U.S.) PMC3 PMC+ PMC
Silver content of clay 90% 90% 77%
Linear shrinkage 10-18% 8-15% 20-30%
Firing conditions 600°C: 30 min +
700°C: 10 min +
750°C-900°C: 5 min +		 800°C: 30 min +
850°C: 15 min +
900°C: 5 min +		 850°C: 2 hrs +
900°C: 1-2 hrs
Recommended
firing method		 Electric kiln
Gas torch
Silver pot
Mini pan		 Electric kiln
Gas torch		 Electric kiln
Purity after firing 99.9% 99.9% 99.9%
* The weight indicated is for the silver content in the clay.
Characteristics of PMC3
PMC3 has the soft texture of clay and is suitable for not only delicate modeling but also for large pieces. It fires at a wider temperature range of 600 to 900 degrees Celsius. The intensity and luster of the fired piece is the highest among all types of PMCs fired under the same conditions.* The advantages come from the fact that PMC3 consists of finer silver particles as the raw material.

Because it can be fired at 600 degrees Celsius, firing with sterling silver (Silver 925)  has become possible, which was not in the past.**

The range of firing temperatures means that simplified firing equipment can be used, like the hand-held gas torch, Silver Pot (using solid fuel as heat source), and Mini Pan (using gas stove as heat source), in addition to an electric kiln. PMC was first developed and marketed by Mitsubishi Materials Corporation.

* PMC3 has the highest sintering property among all commercially available pure PMC silver products (compared with the conventional company products). The photos below display the status of the PMC3 and a conventional PMC after firing.

PMC3 Conventional product

** If you want to fire PMC3 and sterling silver at the same time, always use an electric kiln that can maintain a temperature of 600 to 700 degrees for firing. The surface of sterling silver may turn black (or deteriorated in luster) due to oxidation, but you can simply rub the stain from the surface with an abrasive cloth.
PMC3
1) The clay can be handled for a longer time.
How long the softness of clay can be maintained is one of the most important properties of PMC. If softness is lost, the clay cracks, which makes it difficult to work on. PMC3 maintains the softness for a long period of time due to the binder's ability to retain water.

2) Clay can be easily recovered using water.
Moisture in the clay evaporates little by little due to body and ambient temperature while modeling. As a result, the clay loses softness and elasticity and small cracks are prone to be created on the surface. If this occurs, add a tiny drop of water to recover the clay near to the original state.
PMC3 has the water absorbing property due to the binder. As the clay is hydrophilic, water can penetrate deep into the clay and it can be more easily recovered. Due to this property, the clay is no longer wasted.

Note: When the clay is completely dried and hardened, recovering with water is impossible.

3) The number of problems during the drying process is dramatically reduced.
Drying (evaporation of moisture from the clay) is very important among all the processes of working with PMC. If any moisture is left in the clay, the piece may expand, crack, or even break during the firing process (to burn out binder in the clay and bind silver particles). There are two methods of drying: natural drying for one or two days and artificial drying in a shorter time using driers or other tools. Artificial drying was sometimes unsuccessful and left some moisture inside even after the same period of time, due to such conditions as the shape of the piece (size and thickness) and direction and distance of the drying tool.
PMC3's capability to evaporate and release moisture inside clay during warming has been improved. As a result, the artificial drying time is shortened and the number of problems during firing caused by insufficient drying has been dramatically reduced.

Note: It may help to understand that the water absorbing property described in (2) and the capability to evaporate and release moisture described in (3) are be inextricably linked.

4) Drying temperature determines strength and machinability of the dried piece.
When PMC3 is artificially dried, the condition determines the strength and machinability of the dried piece. Listed below are the relationships between the drying conditions and properties obtained:

Drying temperature Length of time (or change in status) Strength and cutting performance Guide of drying tools
80°C to
180°C		 15 to 30 minutes depending on the size, thickness, and shape of the piece. Dry until immediately after white smoke emanates from the piece. Excellent cutting performance. Can be filed or cut by hand using a file or chisel. • Drier
• Electric hot plate at the drying temperature
180°C to
250°C		 Wait more than five minutes after white smoke emanates from the piece. Excellent strength.
Difficult to file or cut by hand using a file or chisel. Use a hand grinder or other machine.		 • Electric hot plate at the drying temperature
• Electric kiln

Note 1: Avoid drying at temperatures above 250 degrees Celsius because it may decompose the binder in clay and deteriorate intensity significantly.
Note 2: Even when using the guided drying tool, the desired property may not be obtained due to such conditions as distance between the drying tool and the piece and the output power of the tool.

Grinding and cutting the dried piece is easier.
Thoroughly grind the surface of the dried piece using a file or abrasive to improve the quality of the finished piece. Or, cut the dried piece using chisels, cutters, hand grinders, or other tools to produce engraved decorations. Cutting performance of dried PMC3 is significantly improved and grinding and cutting is very easy. Because excessive power to the piece is not added while cutting, damage to the piece during grinding or cutting is prevented and working hours are shortened.

Note: Read the explanation in (4) carefully. The property described there is obtained only by drying at 80 to 180 degrees Celsius.

Characteristics of PMC+ (Quick)
PMC+ demonstrates excellent modeling capabilities, while maintaining the property of clay, which is common to all PMC products. With the lowest shrinkage while firing in the PMC series, PMC+ is second only to PMC3 in terms of intensity and luster.
Characteristics of PMC Standard type
As the ratio of water and organic binder in PMC Standard is higher than any other PMC silver, it is the most clay-like PMC. PMC Standard is elastic and will not easily crack even if worked for longer periods of time. When dried, the clay can be easily recovered by adding water. With PMC Standard, you need to use an electric kiln. The clay displays the highest shrinkage of 20% to 30% (longitudinal) of all PMC silver. You may utilize this shrinkage to produce very delicate pieces.* PMC Standard is the first commercial Precious Metal Clay in the world and is thus a monumental product. Called "Original PMC" in the U.S., it still has many devotees. As long as you have an electric kiln, this PMC Standard is ideal for a beginner.

* You can create patterns and designs on a larger scale, which makes the work easier, and they will be shrunk after fired.
Characteristics of PMC3 Paste type and PMC3 Syringe
The paste and syringe have extremely fine pure silver particles as in PMC3. For this reason, the PMC3 Paste-type and PMC3 Syringe-type also fires at lower temperatures and demonstrates superior intensity and luster after firing. The paste and syringe can be applied to pieces made of PMC+ and PMC Standard as well as PMC3. The table below lists the characteristics, use, and directions:

  PMC3 Paste type PMC3 Syringe type
Characteristics
(purpose of use)
• Excellent strength of fired pieces
• Excellent luster
• For gluing pieces of clay
• For gluing dried pieces
• For gluing fired pieces
• For gluing fired pieces to pure silver parts
• For modification of clay, dried pieces, and fired pieces
• For imprinting technique (The paste is applied to the patterned indented surface and the pattern is imprinted to the clay.)
• As no organic solvent is used, the clay has no offensive odor (irritating odor) and has no harmful effects on human health.
• Purity after firing: 99.9%
• Excellent strength of fired pieces
• Excellent luster
• Excellent shape retention
(The shape is retained after extrusion)
• Purity after firing: 99.9%
Drying One day at room temperature or 15 to 30 minutes or even longer at 80 degrees Celsius.
Driers or an electric hot plate can be used (hot plate must be set at 80 degrees.)		 One day at room temperature or 15 to 30 minutes or even longer at 80 degrees Celsius.
Driers or an electric hot plate can be used (hot plate must be set at 80 degrees.)
Firing 600°C: 30 min +
700°C: 10 min +
750°C-900°C: 5 min +		 600°C: 30 min +
700°C: 10 min +
750°C-900°C: 5 min +
Use with other types of PMC When used with PMC Standard, apply the conditions for the standard. When used with PMC+, apply the conditions for PMC+. When used with PMC Standard, apply the conditions for the standard. When used with PMC+, apply the conditions for PMC+.
Other directions
• When dried, add a tiny drop of water and it will resume the original state. If it doesn't, leave it for one day after adding water, and it will revert to paste.
• It is possible to collect and mix the waste from the modeling process or unused dried pieces into the paste to reuse them. Adjust the viscosity by adding a small amount of water. The paste, however, may not have the advantageous properties of the original PMC3 paste.
• The paste where the dried pieces are mixed may not be used for gluing fired pieces.
• The fired pieces have excellent intensity , but bending it many times may cause it to break.
Characteristics of PMC Sheet
The PMC sheet consists of pure silver particles and binder only, containing no water. The special binder results in elasticity and flexibility without water. The sheet can be folded or cut with scissors like paper. Because it contains no moisture, there are no time constraints-model as long as you like.
If any water is applied or dropped on the sheet, the binder dissolves in water and the sheet may not retain its shape . To glue the sheets, use gum arabic (paste at stationery suppliers).
The sheet contains more binder than clay. Unlike PMC3, it does not fire at low temperatures. Always use an electric kiln and fire for 15 minutes or longer at 850°C or for five minutes or longer at 900°C.

About PMC Silver Discoloration of silver
Drying   Gold paste Aura 22
Firing   Troubleshooting
Shrinkage   Other Information


Mitsubishi Materials Corporation