Firing Art Clay Silver Clay

Preparation before Firing

Allow your grey white pieces of Art Clay Silver clay to dry thoroughly.  If it is not dry enough, bubbling and cracking may occur. Finished pieces should be allowed to dry out fully - give between 24-48 hours in a dry, warm atmosphere.

Alternatively, the clay can be dried in an oven at 180°C/330°F for at least 10 minutes or with a 1200w hair dryer within 3-10cm of the piece for 10-15 minutes.  If you have a kiln, you can dry the Art Clay Silver at 150°C/300°F for 10 minutes.  Do not overheat as there is the possibility of burning away the binders before the silver has fired.

While the item is still warm, you can find out if it has dried fully by placing it on a piece of black stainless steel, glass or plastic.  After 15-20 seconds, any remaining vapour will settle on the surface.  If the item is fully dried there will be no steam residue.  You can download this PDF to find out more about the drying times of each of the Art Clay silver and gold clays.

File and sand the dried item to remove any burrs or nicks. Take your time, the clay is very brittle at this stage and needs to be handled carefully. The better the finish at this stage, the less work there will be at the final stage.

Art Clay Silver 650 is a low-fire clay which means that the clay can be fired from 650°C/1200°F.  The natural binders are burned off at this stage and the silver particles solidify to form 99.9% pure silver.  The finished item can be hallmarked (find out more from the Assay Office).

Tips

• Place items face down for firing, this will protect detailed designs from becoming damaged by overheating

• Fired pieces can be added to.  Use Art Clay Silver paste to attach fired or unfired items.  The silver will not shrink again but newly attached, unfired items will.

• An indicator of over firing is if the item begins to melt or turn red.  Stop the firing process immediately.

• As long as an item has been fired correctly, there should be no difference between shrinkage for gas hob, blow torch and kiln fired items.

• Full drying times and firing instructions for the Art Clay Silver clay are in the packaging or you can download this PDF to find out more

SAFETY:

• Both smoke and steam is emitted during the firing of Art Clay Silver.  The process should therefore take place in a well ventilated room

• The fired silver clay is very hot and should be placed in an appropriate area to be allowed to cool before handling

Firing with a Kiln

The advantage of kiln firing is that you can fire much larger pieces than with the other two methods. You can also fire pieces with core materials such as cork clay and artificial fireable gemstones. You will need a kiln with a thermostat so that the temperature can be held at the right level for the time required.

The Prometheus Pro-1 kiln is large enough to fire ten Art Clay Silver jewellery pieces at a time. The space can be doubled by adding a fibre board shelf placed on two tiny terracotta flower pots.

The kiln can also be put to good use for firing Art Clay Gold, fusing and slumping glass and for melting enamel powders.

To fire the Art Clay Silver in the kiln, you will need to hold the temperature at 800ºC for 10 minutes. Full instructions are in the clay packet or you can download this PDF to find out more about the firing temperatures and times of each of the Art Clay silver and gold clays.

Firing with a Blow Torch

1. Ensure the Art Clay Silver clay is completely dry before firing (allow at least 24 hours).

2. The clay will shrink as it is fired.  This can be used as an indication of whether the firing has been successful.  Place the object on a piece of paper and draw around it.  Put the paper aside so that the size can be compared with the fired item.

3. Place a fibre brick on a ceramic tile or in a heat proof pan.

4. Lay small single pieces up to 25g on a fibre brick.

5. Turn on the blow torch and adjust the flame until it goes yellow, then turn it back to just blue.

6. Angle the blow torch at a 45° angle and direct the flame at the clay, keeping a distance of about 6-7cm.  Use a stroking action to keep it moving backwards and forwards across the piece. It will smoke a little as the binder burns off and blacken in places as the heat builds.

7. When it glows a pale orange, time it for 1 minute (up to 2.5 minutes for larger pieces). The surface will become white all over, continue firing until the time is up. If you see a silvery surface appear when firing with a torch, the flame is too close and the silver is beginning to melt. As long as you pull the torch away quickly the piece will not be damaged.

8. Allow to cool for at least 20 minutes before moving.

9. Place the fired Art Clay Silver onto the piece of paper on which you drew the outline.  The item should have shrunk by 8-9%.  If there is no obvious signs of shrinkage, repeat steps 4-8.

We do not recommend using small brulee torches or the pencil type blow torch for firing Art Clay Silver - these may not reach the high temperatures required and the fired silver will not be strong enough.

Firing on the Hob

Art Clay Silver can be fired on a domestic gas hob or on a camping gas stove, although the method is not suitable for pieces with a cork clay core, or with artificial gemstones larger than 5mm, these items should be fired in a kiln.

1. Ensure the Art Clay Silver clay is completely dry before firing (allow at least 24 hours).

2. The clay will shrink as it is fired.  This can be used as an indication of whether the firing has been successful.  Place the object on a piece of paper and draw around it.  Put the paper aside so that the size can be compared with the fired item.

3. For pieces up to 30g (no larger than 5cm x 3cm x 2cm) and up to 6 items, lay a stainless steel mesh on the burner and place the fully dried items where the flames are strongest, cover with more mesh for added safety. If you do not have a cover, wear eye protections in case the clay spits.

4. Turn the gas burner on full and use a skewer to push the pieces into the areas of the mesh that glow red. After a few minutes, the clay will smoke a little as the binder burns away and it will take on a pale orange glow. Now time the firing for five minutes while the piece continues to glow.

5. Turn off the gas and allow the fired pieces to cool for 20 minutes in situ.

6. Place the fired Art Clay Silver onto the piece of paper on which you drew the outline.  The item should have shrunk by 8-9%.  If there is no obvious signs of shrinkage, repeat steps 3-5.

Finishing the Fired Silver

The fired piece will now appear to have a white matt coating. This is the silver which has to be burnished or brushed to create the shiny surface. The tools you use will depend on the finish you want.

A fine stainless steel wire brush is the best place to start, then sand paper, starting with the coarser grit and working up to the finer grit until the surface is smooth.

The final tool to use after all scratches have been removed is a burnisher. Rub the surface with the burnisher to harden and smooth the silver and to give it a mirror shine.