Blog post #139 Silver Clay

I love taking classes in disciplines that I don’t normally work in and just recently I went on a course to learn about silver clay. The one-day course was held at the Ardington School of Crafts in Oxfordshire (www.ardingtonschool.com), which is owned by the incredibly talented Simon Sonsino, who I know fairly well. The team who ran the course can be found on Facebook at www.facebook.com/IMadeItCrafts or on their website https://www.melanieblaikie.com/

I took the class with my lovely and very talented friend, Teresa Munn, who is a ceramicist. We take classes together so that we can learn something new and spend the day with each other. Such fun! We have been wanting to take a silver clay class for some time; Teresa as she works with clay all the time (check her work out at https://www.teresamunn.com/) and me because, many years ago, I studied silversmithing at night school. It was an expensive hobby and so wasn’t something I continued with but loved doing it at the time.

Silver clay is a product invented in Japan in the 1990s. It is formed by recycling fine particles of silver, a byproduct of the photographic and X-ray industries, and combining them with water and an organic binder. It handles like clay in that it dries quickly once removed from its packaging, so careful handling is required to stop it from drying out before you can properly use it. Don’t be put off but just be aware.

In the class we were given pots of Play-Doh and encouraged to make our designs with that before handling the silver clay as Play-Doh doesn’t dry out. The class leaders provided mini rubber stamps and mini pastry cutters along with various small items for rolling and mark making. Once we had come up with our designs, we were allowed to open the packaging and remove the clay.

Working quickly, we made the same design as we had with the Play-Doh and then, as time was limited, we dried the silver clay using a hair dryer for about five minutes. Normally, it is best to leave it overnight to dry gently. At this stage, the silver clay is very brittle and needs careful handling. Any rough edges can be filed or smoothed off and, with extra care, additional marks can be added.

There are a few ways to take the product from dry to silver. If you are already familiar with clay and use a kiln, placing the clay in a hot kiln is one way (the recommended time and temperatures are 30 minutes at 650°C on a continuum to only five minutes at 800°C). Another way is using a butane torch. You will need to spend two or three minutes getting the clay up to temperature but watch carefully and a little puff of smoke will escape from it. That is the water and binder burning off which means a few more minutes and everything is sealed and done.

If you don’t have a kiln or a butane torch, a kitchen crème brûlée torch will be just as good. Alternatively, you can simply place the clay on a wire mesh over your gas hob and, making sure the flames are touching the clay, heat it until you see that puff of smoke. It might take a bit longer than the gas torch, but it works.

Once done, the silver pieces can be polished using a burnishing tool or a teaspoon to bring them up to a lovely shine. Do be aware that you will get about 10% shrinkage with this product but then they are then ready to wear.

A bit more information about this fairly new product. Silver clay is of such high quality that it can be hallmarked at any UK Assay Office, which will currently cost you £10 per item.

There are two types of silver clay, which differ in terms of quality. Type 925 is regarded as sterling silver and if you use this product you will need to fire it in a kiln to harden it. Type 999 is called “fine silver” and is almost pure. The Assay Office will not give a 1000 purity number so 999 is the closest (and best) you can get. An interesting fact is that sterling silver does, as we all know, tarnish. It is the copper content – around 7.5.% – which causes the discolouration and tarnishing, not the actual silver.

With 999 fine silver clay, you don’t get any tarnishing. So, if you have a piece of “silver” jewellery made in the last 25 years, don’t assume that it is not silver if it doesn’t tarnish. It could easily be virtually pure silver.

On this one-day course I only worked with simple silver clay, but I did buy additional products to play with at home, one of which is silver clay in a tube. This softer version of the clay I experimented with allows for fine lines to be drawn, dots and dashes to be made and is slightly more flexible. It is a little bit thicker than toothpaste; it holds its shape when squeezed out of the tube and there are different-sized nozzles which allow for varying line thicknesses etc.

This is particularly useful if you want to set a stone into your silver as you can draw the setting, heat up the silver and then set the stone in the setting using a burnishing tool. Teresa makes beautiful bowls using clay slip, which she writes the stories of refugees who have arrived in this country. Using silver clay in this form would give her a far stronger product which could be even more delicate than the pieces she currently makes. Also, you can use this clay in a tube to make repairs to your other silver pieces.

Other products available are silver paste, which is a creamier version of the clay in the tube and is perfect for repairs and filling in cracks. You can also use it to stick unfired pieces together, making it a very flexible product. Something else you can do is to coat leaves, or a textured surface you like, to make a silver replica of your chosen subject. Moreover, the paste is apparently designed to use on ceramics, porcelain and glass and will bond during firing so that it will stick on.

There is also a silver oil paste which can be used to attach metals to each other which is particularly good for repairing but apparently gives a stronger bond than normal paste. There is a thinning liquid which you get with it to use if the paste dries up.

When I am feeling flush (as I suspect this product will be very expensive), the gold version of this clay sounds fabulous. It apparently works the same way as the silver, but you do need a kiln as it needs to be fired to 990°C for one hour. This product will shrink by about 15%

The paste version is pure gold in liquid form, and you can paint it onto your existing pieces, fire, burnish, and polish giving you a 22 or 24 carat gold finish. A word of warning.

Finally, there is a silver paper product. Really, what will they develop next?  This product is dry and feels slightly rubbery to the touch. The paper is very thin and flexible, allowing you to fold it origami-style, but you can also cut it or layer it to make thicker sheets of paper.

When used on its own this paper does not need to be dried but can go straight into the kiln. If the paper cracks whilst you are making with it, don’t try and fix it by adding water; it won’t work. Simply fire the paper and repair it with one of the other products discussed above.

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