Firing Art Clay Silver Clay

Preparation before Firing Art Clay Silver Clay

Great News! Although the following still applies to Art Clay Silver Clay, the New Art Clay Silver clay formula has increased the working time of this product! See our “New Formula Art Clay Silver Clay – Tried & Tested by Joy Funnell” page to find out more!

1. Allow your grey white pieces of silver clay to dry thoroughly – this applies to all the Art Clay Silver clays including the new formula Art Clay Silver and Art Clay Silver 950. If it is not dry enough, bubbling and cracking may occur. Finished pieces should be allowed to dry out fully in a dry, warm atmosphere for 24-48 hours. 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 5-10cm 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.
2. While the item is still warm, you can find out if it has dried fully by placing it on a piece of 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.
3. 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.
4. The new formula Art Clay Silver clay is a low-fire clay which means that the clay can be fired from 650°C/1200°F using a blow torch, gas hob or a kiln. 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). The professional Art Clay Silver 950 must be kiln fired only, once fired the 92.5% silver can be hallmarked as sterling silver.

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.

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 on the Hob (browse Firing Tools)

Art Clay Silver clay can be fired on a domestic gas hob or on a camping gas stove. Pieces with a cork clay core, or with artificial gemstones larger than 5mm, should be fired in a kiln.

1. Ensure the Art Clay Silver clay is completely dry before firing.
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 lit burner and observe where the flames are strongest. Using tongs, place the fully dried items on the hottest parts of the mesh and 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 up and wait a few minutes. The clay will smoke a little as the binder burns away and takes on a pale orange glow.
5. Time the firing for five minutes while the piece continues to glow.
6. Turn off the gas and allow the fired pieces to cool for 20 minutes in situ.
7. 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.

Firing Silver Clay Pieces with a Blow Torch (browse Firing Tools)

Blow torch firing is suitable for Art Clay Silver pieces up to 25g. It is not suitable for projects made over cork clay, paper clay, or large quantities of organic material, as well as projects that include glass, porcelain, ceramic, natural gemstones, or other heat sensitive materials. Never fire plastic as it creates toxic fumes.

1. Ensure the clay is completely dry before firing.
2. The clay will shrink by 8-9% 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 your silver clay piece on a fibre brick on top of a ceramic tile or in a heat proof pan.
4. Turn on the blow torch and adjust the flame until it goes yellow, then turn it back to just blue.
5. 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.
6. When the piece begins to glow 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.
7. Allow to cool for at least 20 minutes before moving.
8. 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 with a Kiln (browse Firing Tools)

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.

Please note that it will take approximately 15 minutes for room temperature kilns to reach the necessary firing temperatures.

How to kiln fire Art Clay Silver Clay

1. 1. Put your dry silver clay creation in a room temperature kiln, and set the kiln temperature to the following and fire for the recommended time:
      

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      Firing Temperatures and Times for Art Clay Silver Clay:

      650°C/1200°F for at least 30 minutes
      700°C/1290°F for at least 15 minutes
      750°C/1380°F for at least 10 minutes
      800°C/1472°F for at least 5 minutes
      

   2. Turn off the kiln and wait until the kiln temperature drops to 200°C (392°F).
   3. Take the fired silver clay out of them kiln and wait until it cools down completely (or leave it until the kiln
      temperature drops to room temperature) before polishing or burnishing.

How to kiln fire Art Clay Silver 950 Professional Clay:

1. 1. Put your dry silver clay creation in a room temperature kiln, and set the kiln temperature to 500°C (932°F).
   2. Ramp up until 500°C (932°F) and hold the temperature for 30 minutes.
   3. Set the kiln to 870°C (1598°F) and hold the temperature for 60 minutes.
   4. Turn off the kiln and wait until the kiln temperature drops to 200°C (392°F).
   5. Take the fired silver clay out of them kiln and wait until it cools down completely (or leave it until the kiln
      temperature drops to room temperature) before polishing or burnishing.

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. Start with the coarser grit and work 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.

Visit the the Clay & Plaster & Modelling Tools section of the website to browse the range of Art Clay Silver clays, jewellery findings and tools.