Adam Hunter


Metal clay is a suspension of tiny particles of metal in a clay binder, which can be used to make jewellery, beads and small findings. The beauty of metal clay is that it can be manipulated in the same way as any modelling clay, but once fired the binding agents are burnt off leaving the metal form intact. Although there is a certain amount of shrinkage (between 10-15% for the more modern versions), very fine detail can be achieved, including impressions that would require casting in any other method of metalwork.

Silver metal clay results in objects containing almost pure silver (also known as fine silver) which is ideal for enamelling. There are two popular brands available – Precious Metal Clay (also known as PMC) and Art Clay Silver (ACS). Precious Metal Clay was developed in the early 1990’s in Japan and consists of microscopic particles of pure silver (or fine gold powder) and a water-soluble binder which burns off during firing. The original formula of PMC (now called ‘Standard’) has to be fired in a kiln at a temperature of 1650F and has a high shrinkage rate of around 30%. Two additional versions were later developed called PMC+, which can be fired at 1490F and PMC3, which can be fired at temperatures as low as 1100F. Both of these later versions of PMC have much lower shrinkage rates, allowing much finer detail to be worked into designs.

Art Clay Silver (ACS) was also developed in Japan and is similar in consistency to PMC+. The main difference with ACS is that it can be fired using a hand-held torch or gas oven. Because of subtle differences in the binder components and the longer firing times, ACS benefited from having a considerably lower shrinkage percentage – only 8-10%. This means that ACS can be worked in more detail without any loss of definition in fine work. Art Clay Slow Dry was introduced soon after, which has a much longer working time before requiring firing, allowing intricate work to be moulded into the clay with no loss of malleability.

Art Clay 650 and Art Clay 650 Slow Dry are now becoming increasingly popular, as not only do they have a longer working time but can be fired at temperatures as low as 650C/1200F. This allows jewellers to incorporate glass and Sterling Silver into the designs without fear of damaging the components. AIDA, the manufacturers of ACS have also introduced Oil Paste, a product only used on fired metal clay or milled fine silver, and Overlay Paste which is designed for drawing designs onto glass and porcelain. These two products have allowed the use of metal clay products to be incorporated into a whole new range of designs and mediums, expanding the potential of this product.

Metal clays allow jewellers to work with a material that is as malleable as ordinary modelling clay but produces fine (almost pure) silver jewellery of exquisite intricacy and beauty. Once polished it has a lustre and shine that is easily comparable to cast silver and because of the development of the products over the last few years shrinkage is now no longer an issue. The type used depends on personal preference as both types have their advantages, but incorporating metal clays into your jewellery design gives you a new medium to explore with beautiful results.

Adam Hunter


In the 1990’s scientists in Japan developed a combination of binders and fine metal particles to create a material with the malleable properties of modelling clay, known as Precious Metal Clay (PMC). This product is now available to the jewellery making industry and to hobbyists as well.

PMC is also commonly known as ‘Silver Clay’ which, when heated, turns into pure silver. The binder in the material holds the silver particles together. When fired like normal modelling clay, the binder burns away, allowing the silver particles to bond and form a solid piece of pure silver. The beauty of Silver Clay is that it can be easily used at home with just a few specialist pieces of equipment, and can bring a whole new dimension to your jewellery making techniques.

Since its initial development, Silver Clay has undergone a transformation, making it easier than ever to use. Early examples of the clay needed to be fired at very high temperatures, requiring a kiln to complete the process. Modern metal clays are now capable of being fired in a common kitchen oven or even with a gas blowtorch. Although a kiln is not strictly necessary with modern materials, it is still a useful jewellery workshop item to have, as it enables the user to control the temperature of the firing accurately. Too high and the silver will melt into a blob. Two low and the binder will not burn off completely, leaving the final piece weak.

The early PMC suffered from one major drawback – shrinkage. Modern metal clays are now much more resistant to shrinking during the firing process, making them easier to manipulate into far more delicate and complex patterns. Acceptable levels of shrinkage for modern materials are between 10-15%, depending on the brand.

Metal clay can be thinned with water to make a paste that can be used to join elements, repair cracks and use as a surface texture. Because the clay is very dense, just stirring in additional water will not thin the mixture. The medium has to be mixed, rather like adding thinner to oil paint, with a palette knife. Once the required consistency has been reached, allow the mixture to ‘rest’ in an airtight container for a few hours before use.

Metal clay is perfect for developing texture in a piece, and this can be achieved by simply pressing the pattern into the surface of the clay. Patterned rollers, even leaves or lace can be used to achieve a delicate finish on the surface of the silver piece.

Firing temperatures for the clay are around 1500 degrees F, which is applicable for most types of metal clays. Firing time is around ten minutes, making the use of a small kiln the optimum choice for firing processes.

Once fired, the metal can be soldered, filed, sanded and polished like any other metal, but it is advisable to burnish the surface first to compact the surface structure. Once finished, the piece can be worn like any other piece of silver jewellery.

Silver clay is widely available from jewellery and craft suppliers, the two main brands being Precious Metal Clay (PMC) and Art Clay Silver. Gold clay is available, but its price is prohibitively expensive for novice users. The silver clay is a good starting point when exploring this versatile medium.

Adam Hunter


Precious Metal Clay (PMC) made its first appearance in the 1990’s and has become popular in jewellery making. The clay is a combination of binders and tiny particles of precious metal suspended in the clay.

Once heated, the binders burn off, allowing the particles of metal to combine and resulting in a solid metal piece. The most common type of PMC is silver clay, although gold and even bronze clays are available (the gold clay being very expensive).

This remarkable material means that you can create solid silver or gold items of jewellery as easy as using any other form of modelling clay. (Do be aware, however, that there is around a 10-15% shrinkage rate during firing.) The possibilities with PMC are only limited by your imagination.

The surface of PMC accepts impressions extremely well, allowing you to give your pieces texture and patterns. By using patterned rollers or any item that comes to hand such as lace, leaves or even bark, you can create a textured surface in silver or other metals that would be difficult to replicate without the use of specialist equipment. Once the clay has been fired and finished, the pattern will be clearly visible on the surface. This is a perfect way of making interesting and unique beads, for example, or for creating a patterned finding for a broach.

With practice and skill, PMC can be utilised in fine work such as filigree or cloisonné, but do remember that the PMC will shrink during firing, so be sure to allow for this in the initial stages.

One of the easiest pieces of jewellery to make with PMC is a bangle. By simply rolling out the clay, placing your design on the surface and joining the ends, a beautiful silver bracelet can be produced in a very short time. Once the clay has been fired, it can then be polished and finished to produce something that will complement any outfit.

PMC is most often used to produce silver beads, again lending itself perfectly to this application. The blank shapes can be easily produced by hand, or, if you want to add a more complex design, by using a mould. Once the basic form has been made, it is simply a matter of placing a hole through the bead and firing. The temperature for firing PMC has to be carefully monitored though – too low and the binders will not completely burn off, leaving the finished item vulnerable to breaking or crumbling, too high and the metal will blob, leaving you with an ingot and nothing more. The usual firing temperature of PMC is 1500 degrees F, so the use of a kiln, which will enable the user to monitor the temperature closely, is advisable.

PMC has proved to be so popular in jewellery making that a number of guilds and organisations have developed around its use. The PMC Guild has a wealth of information, video clips and project ideas available on its website to help you get started, including tips on how to work with this versatile material and incorporate it into your jewellery making.

Christian Garrington


Precious metal clay (brand names are PMC and Art Clay) is modern-day alchemy. PMC is a clay base with tiny pieces of silver suspended within it that, when heated, burns off the clay leaving a solid silver residue. The clay base acts as a binder for the metal particles. Once this has been removed, the remaining silver particles bind together, giving you the finished product.

The real beauty of precious metal clay is that it can be manipulated like any ordinary modelling clay, making it perfect for jewellery making. The modern precious metal clay can be using a jeweller’s torch, as the firing temperature is much lower than the early versions of this clay. However, a small kiln will produce a much more constant temperature range and can be controlled exactly, meaning that the results will be more consistent.

Precious Metal Clay once had a very bad reputation for shrinkage, making it unsuitable for fine work or detail. Modern precious metal clays have a much lower shrinkage rate (around 10-15%), but you still need to factor this into the final piece to ensure that really fine detail is not lost in the firing process.

Once fired, the silver piece will seem very lacklustre and dull, so it will need finishing. The dull matt surface hides the real beauty underneath, so finishing and polishing will reveal the shining silver below. When soldering finished precious metal clay pieces it is essential to remember that the surface will be more porous than standard sterling silver, so it is best to burnish the piece prior to soldering. But because it is almost pure silver there is little risk of fire stain on the surface and the final results are almost indistinguishable from sterling silver.

Because precious metal clay is a clay, it takes impressions very well. A design can be pressed onto the surface of the clay and be revealed in the final silver piece. Patterned rollers, lace or even leaves can be used to create unique effects that are difficult to reproduce in ordinary silver unless it has been cast. Precious metal clay is a popular way of making silver beads. The clay can be formed into beads, decorated with a surface pattern and then fired in a kiln quickly and easily, producing high quality silver beads.

Safety considerations have to be taken into account when working with precious metal clay because of the high temperatures required to fire the clay. A small enamelling kiln allows you to safely achieve the temperatures required for optimum results, but ensure that you have all the correct equipment such as tongs with heat resistant handles to extract work from the kiln safely and a heat-proof surface upon which to work.

Precious metal clay is an ideal medium to work in if you want to create pieces of silver jewellery that are unique to you. The only thing that limits you is your imagination. Precious metal silver clay is widely available from good jewellery equipment suppliers. There are two main brands – Precious Metal Clay and Art Clay Silver. The clay is also available in other metals including gold, but the cost is significantly higher than the silver clay.

Adam Hunter


Before soldering there are three factors which must be considered. The design must lend itself to soldering, parts to be soldered must fit closely and accurately and the correct solder and flux must be used.

Solders are typically classified according to their melting points – easy, medium and hard. This therefore refers to the ease of melting the solder. Hence an easy grade solder melts before a hard grade one. This can be used where a sequence of joints are to be made. Usually a solder must conform to the same hallmarking rules as the metal being joined – for example, a 9ct solder must contain at least 37.5% gold. However, there are some concessions such as Platinum Solders and some white gold alloys.

Gas and compressed air mixtures are generally the most satisfactory for torch soldering. Fine adjustment of flame size and temperature are possible. The flame should be kept constantly on the move over the whole joint area, or over as wide an area as can be conveniently joined, in a single application of solder.

The joint areas must be free from dirt and grease, and ideally cleaned with a file or emery paper to ensure the solder will wet the parent metal. Flux should be applied to the joint area and solder prior to heating. Fluxes promote wetting of the workpiece by the molten solder. This is done by removing any oxide films present on both the parent metal and solder and prevent further formation of oxides during heating. The flux must be completely fluid and active before solder liquidation and should remain so until after the solder solidification.

If the size of the joint is large further flux additions may be made during the process. It must be noted that warming of the workpiece may be required to ensure full retention of the flux paste over the whole joint area. The torch should initially be held some distance from the workpiece so that the flame heats the work generally. If components of different size are being joined the torch should predominantly heat the heavier item.

There are two general techniques used to apply solid solder. Preplacement is where small pieces of solder are placed at the joint seam prior to heating. Heat is then applied until the solder flows into the joint. Feeding is where the fluxed joint is heated to temperature and tip of the solder wire is fed into the joint and should melt on contact.

Using both these techniques the joint should be heated more strongly than the remainder. The time and temperature required to complete a joint must be kept to a minimum.

Gold and silver flux residues may normally be removed by soaking in hot water. Any further residues that persist may then be removed by brushing. In difficult cases the workpiece should be impressed in 5 – 10% sulphuric acid solution for 2 – 5 minutes, rinsed in hot water and brushed again. For large scale soldering a small furnace may be used to provide sufficient uniform heat to the workpiece. For mass production batch or conveyer type furnaces may be used. However, the quantities of components to be soldered must be large enough to justify the relatively high capital expenditure and development of a method for each particular soldering operation.

All workpieces can be successfully finished by the standard practices and processes currently available. It must be noted that powdered borax does not always meet the requirements for all applications, where the extensive range of other solders now available may be used.