Firing facts

[Todd]

Before firing make sure your Art Clay Silver project is completely dried.  If you just air dry, this can take between 1 hr to a full day depending on your local humidity, the thickness of your piece and your personal work methods.  You can use a food dehydrator or other sorts of drying equipment as well. It is important that the temperature stay below 200°F so that the water doesn’t boil and distort your piece, further - the temperature must stay below 450°F or the binders will burn off and cause further damage to the piece. If your piece is not completely dry, you will have significant problems and distortions when you fire it. Note that ACS Slow Dry take 5 times longer to dry then the regular drying clays.

TORCH – I use a small butane filled hand-held torch, very portable, reasonably priced and easy to transport to workshops and demos. There are a lot of torches out there but the firing of your work is based on your control of the torch --- sooooo....  If you are careful and have good balanced control of your torch, you could use whatever torch you have on hand.  The main feature of a torch to use for firing Art Clay is to have a large enough flame cone to bath your piece in the heat.  Really small flame tips will tend to be very hot in too small of an area, making them hard to use and get the entire piece up to an even controlled firing temperature.
You start heating your piece(s) with the torch. Shortly after you start, as the temperature raises to around 450°F, the organic binders will smoke and flame and burn off. I usually back off the torch for a short period and let this happen.  Now you can take the piece up to firing temperatures. You judge these by the middle red-orange color of the piece [see FIRST FIRING NOTE below] – then you need to ‘hold’ or keep the piece at that temperature for 1 and ½ minutes. For larger pieces, you will need to ‘hold’ the temperature longer. If you get too hot, the piece will begin to ‘sweat’ and melt into a blob. One indicator of getting too hot is if the surface starts to look wet or liquid shiny – time to back off a bit with the torch. You can torch fire up to about 25 gms of Art Clay Silver.  25 grams makes a pretty good size piece.
You can fire Cubic Zirconium stones directly into the clay. You can do this with a torch, but take it a little easy and cautious on the heating up phase.

STOVETOP– You will need a stainless steel net or screen and a small cover cage. [do not use aluminum with or around ART CLAY] Place the stainless screen on your stovetop gas burner and let it heat up.  You will see red-hot areas; remember where these are (or draw a little map) and let it cool down. Place your pieces where the hot spots were, cover with the cage, and turn it up again.  Let this fire for 5 minutes or so. Start timing when the pieces begin to glow. The time is dependent on the size/thickness of the piece.  Let it cool off for 5 minutes and then using a tweezers, pick up the hot piece and quench it in water. Then you can proceed with your cleaning and finish work. Also, with some of the  "newfangled" gas stoves, the grate is too high for the clay to ever come to an orange glow without removing the grate and putting the stainless mesh directly on the burner.

Barbecue – Using a gas fired barbecue is basically the same as stovetop firing. You will need to test and move the grate around to find the hot spots.
 
KILN - The kiln we are referring to here would be a programmable computer-controlled kiln, basically designed to fire metal clay products. There are several on the open market at this time. The Standard ACS products fire at 1472F for 30 minutes; 1560F for 20 minutes or 1600F for 10 minutes. The ACS 650 product line fires at 1200F for 30 minutes and for shorter times at higher temperatures.  If you are firing other metal clay products, make sure to read the manufacturer’s instructions – they are all a little different. Note: Cork clay armatures, large or thick pieces, large pieces of organic material and/or most stones and glass inclusions require a kiln for firing.

Regarding stones: If you have natural stones, you can test fire them in a kiln at the temperature you will be firing your ACS piece. This can damage or destroy your stones, but if they survive you can build them right into an ACS piece and fire them in places.
FIRST FIRING NOTE
So you have your torch and you are ready to get started with firing some pieces but you never did it before.  A small short firing test will help you. Make a roll or worm of ACS about an 1/2 inch or so long.  Cut it in half and dry both pieces.  Then set up your firing supplies and fire both pieces together for the appropriate timing.  This wo8uld be where you take your pieces up to that middle orange glow as described above. If you hate the idea of just using the clay for this, make 2 small matching beads. Once you finish the firing time [about 1 1/2 minutes] take one of the 2 items you just fired and push it aside. Now start heating the remaining one up again. Go  slow but just keep heating, You want to melt this one, but do it slowly so you can observe all of the stages and effects of the piece melting.  This will give you a good sense of what to watch for so that you don't over fire and melt one of your good pieces.