Firing Tools for Metal Clay

Firing Tools

Fine silver clay offers the most choices in firing options. This is because fine silver is a metal that does not oxidize when heated. Other clays, such as bronze and silver alloy clays contain copper and can only be fired in a kiln. <br? <br="">The best method for firing any type of metal clay is in a digitally controlled table top jewelry kiln because the firing is precise and results in an object that is as dense and strong as possible. But there are other options to fit your budget or lifestyle. The list below describes the firing option available, suggested accessories and the clays each is capable of firing.

Table Top Jewelry Kiln

Either a digitally controlled kiln or one with an infinite control knob can be used for firing any kind of metal clay.
Capabilities: Gold, Fine Silver, Silver Alloy, Bronze, and Copper clays


Digitally Controlled Kiln: features an electronic controller that is programmed by the user for the specific clay to be fired, leaving you free to do other things while the firing is carried out from start to finish by the controller. Digitally controlled kilns are the gold standard in metal clay firing. If you want to do it right, get this type of kiln.

Manually Controlled Kiln: does not have an electronic controller. Manual kilns use what is called an "infinite control knob" to select the temperature. An infinite control knob, while it sounds fancy, is just like the temperature dial on an oven. Simply turn the knob to the desired temperature and turn the unit on. The drawback is that this type of controller is not automatic. It does not maintain the correct temperature automatically. It will drift above and below the target temperature and must be adjusted up and down every few minutes throughout the firing to maintain the target temperature. This can be a drag on the user since it requires babysitting the entire firing.


Kiln Furniture

The tools used in any type of kiln, called "kiln furniture" are the same. For most fine silver clay firings, all that is needed is a kiln shelf and 4 kiln posts. Set the wares directly on the kiln shelf, set the kiln shelf on the posts and fire. For other clays, more tools are needed.


Kiln Shelf: There are several choices for kiln shelves. The difference in price reflects the life-span of the shelf. Inexpensive ceramic fiber shelves break down fairly quickly and must be replaced. If you fire silver clay occasionally, you can easily get away with a ceramic fiber shelf. A hard ceramic shelf is about twice the price, but lasts a lifetime (or until it's dropped!). Kiln shelves can be placed directly on the kiln floor, but it's better to place shelves on "posts" to allow for heat circulation for a more even heating. Soldering boards should not be used as a kiln shelf.
Used with: Gold, Fine Silver Clays

Kiln Posts: A kiln post is something that is used to elevate the kiln shelf so heat can circulate around it, which results in more even heating of the wares. Purchase in a set of 4. Use one post below each corner of a shelf. Kiln posts are available in 1/2 inch, 1 inch and 2 inch lengths. 1/2" kiln posts are all that are needed to elevate a single shelf. 1 inch posts can be used to separate shelves when more than one shelf is fired in a load. 2" kiln posts are usually used to separate kilns shelves when more than one shelf is fired in a load and additional space is needed for taller items being fired. A 2" kiln post can also be laid on its side to make a 1" post out of it since they are 1" wide. While a kiln shelf can be set directly on the kiln floor, using posts makes it much easier to remove the shelf from the kiln.
Used with: All clays


Fiber Blanket (or Doll Prop): When firing pieces that are hollow, round or need some support, they can be nestled on a fiber blanket to cradle them while firing and avoid a flat spot from sitting on a flat kiln shelf. A fiber blanket can only be used a couple of times before it breaks down and has to be discarded. You'll have no trouble recognizing when it's time to discard and replace your fiber blanket.
Used with:
 Gold, Fine Silver Clays

High Temperature Firing Dish with Alumina Hydrate or Vermiculite media: A high temperature firing dish is traditionally used to melt metals, so they are designed to be heated to high temperatures over and over. For silver clay firings the dish is filled with alumina hydrate media (which is grainy or powdery) or vermiculite (which has larger particles) and pieces that need support are nestled in the media. The dish is set directly on the kiln floor, or can be set on a kiln post or a kiln shelf. Some recommend using flower pot bottoms for the dish, however terra cotta is a low-fired bisque that cracks and breaks within the first few firings and has to be discarded, not to mention that your kiln will need to be cleaned of the spilled contents.
Used with: Gold, Fine Silver Clays

Welding or Kevlar Gloves: When a firing is complete, the inside of the kiln will begin to cool, but it can take some time. For those who are in a hurry to get their treasures out of the kiln and finish them (who isn't!), gloves protect your hands from nasty burns. Gloves can be used to remove the kiln shelf from the kiln while it's hot. If you use leather gloves, get the super insulated welding type. A standard leather work glove will not give you the protection from heat that is needed. A welding glove is big and bulky, but will save your hands. Kevlar gloves are constructed from high temperature Kevlar material with a leather covering and will protect your hands even if the kiln shelf is red hot.
Used with: All clays


Enameling Kilns

The two models available are the Amaco Enameling kiln and the Ultra Lite Beehive kiln. These tiny table top kilns are mainly used for enameling, keum boo and granulation techniques, but are also capable of firing silver clay. Firing is limited to small, flat pieces. Rings and beads can be fired, but they need to be turned and fired once on each side.
 Fine Silver Clays


Amaco FA5E Enameling Kiln: The Amaco FA5E kiln has a 6" diameter heating element. The manufacturer claims the kiln will heat to and maintain 1600F, but the surface of the elements will be closer to 1700F and can easily melt silver clay. Silver clay should not be placed directly on the heating element. Place silver clay items on a firing screen to raise them above the elements. This kiln can handle as many pieces as you can fit on the firing screen. A small piece of fiber blanket can be used to support beads.

The Ultra Lite Beehive Kiln: The Ultra Lite has a 3" diameter heating element. Silver clay pieces should not be placed directly on the heating element. For silver clay firing, the Ultra Lite requires special ceramic inserts placed on the heating element, and to control the temperature, the optional temperature control is needed. The kiln can run extra hot in areas where voltage is higher than 110V. The kiln is normally operated with the lid on to create the highest temperature, but in places where voltage is higher than 110V (in the US voltage ranges from 110 to 120V), it can run hotter than 1650F, which will melt silver clay. In this case, the lid is left off.

Firing Screen: Used as a kiln shelf for the Amaco kiln. Place the screen on top of the kiln chamber, or fold the corners of firing screen down 90 degrees so it fits into the firing chamber of the kiln. The folded corners will act as the legs for the firing screen. Place the silver clay items on the screen, cover and turn the kiln on. Set your timer and add 15 minutes to compensate for the time needed to heat the kiln to temperature. After the firing is complete, unplug the kiln and allow the pieces to cool a few minutes before removing with fibergrip tweezers.

Fibergrip Tweezers: Use to pick up and move hot silver clay pieces.


Stove Top Firing

Limited to small, flat pieces, no larger than a quarter. A firing screen is placed over a gas burner. The burner is turned on to locate the places where the screen glows. Note the spots, then turn off the heat. Silver clay items are placed on the "hot spots" with fibergrip tweezers and the heat is turned on again. Timing begins immediately. Fire for no less than 10 minutes. Do not attempt to bend or form stove fired silver clay.
 Fine Silver clays



Hand Held Butane or other Torch

A small butane, propane or jewelers torch is used to heat and maintain a salmon colored glow to the silver clay piece. The torch is raised to reduce heat and lowered to increase heat and maintain the proper sintering temperature. Fibergrip tweezers are used to turn larger pieces and rings for proper sintering on both sides. A hand held torch can also be used with a high temperature firing dish and fiber blanket for firing beads and other items needing support. Since firing tends to be very short (2 to 5 minutes), the strength of the pieces are much less than those fired in a kiln for 2 hours. Do not attempt to bend or form torch fired silver clay.
 Fine Silver, Copper clays


Hand Held Butane Torch: Also called a micro torch or creme brulee torch. Must be able to reach and maintain a temperature of at least 1110F. Always use at least a triple refined butane gas. Anything less than a triple refined butane will quickly clog the flame nozzle and render the torch useless. Good quality butane can be found at plumbing supply, jewelers' supply and cigar stores. Some kitchen supply stores and home improvement stores carry a quality butane as well. Note: if the can does not say "triple refined", it isn't!

Soldering Board or Kiln Shelf: Any type of kiln shelf or soldering board can be used for torch firing. Place the shelf on a heat-proof surface. Place the silver clay object on the shelf and heat to a salmon colored glow and hold for 2 minutes minimum.

Fibergrip Tweezers: Used to move and turn pieces while hot.



Carbon Firing

When firing copper-bearing clays, a special high-temperature container is needed. The container is used to hold activated carbon. Items to be fired are buried in the carbon, covered with a lid and the whole unit is placed in the kiln, ideally on kiln posts to allow for heat circulation. If the kiln is not large enough to accommodate posts, the pan can be fired on the kiln floor.
Used with: Silver Alloy, Bronze, Copper clays


Firing Pan: The type of pan normally used is called a Bain Marie or Steam Table pan. They are a heavy gauge stainless steel containers that are available in a tall or short version. The drawback to this type of pan is that it flakes in the kiln, called "spalling", which makes quite a black, sooty mess. The kiln must be vacuumed after each firing to keep it clean. The pan will spall even after it has cooled and been removed from the kiln, so the work area will also need to be cleaned.

Firing Fork: When using a firing pan, a firing fork is used to handle insert and remove the pan at a safe distance from the heat.

No-Flake Firing Box: This is a firing box that is made from No-Flake Firing Foil, which is a special high-temperature material that does not spall. It will darken, but it will not make the mess that the standard stainless steel pans make.

Firing Tongs: When using a No-Flake Firing box, firing tongs are used to move the box in and out of the kiln.

Activated Carbon: Activated carbon has the unique ability to adsorb oxygen, and what a lucky break for metal clay artists! The entire reason that metal clays containing copper are tricky to fire is because copper oxidizes very quickly when it's heated in the presence of oxygen. Since we are surrounded by oxygen, it means that any time copper is heated with a torch or in a kiln, it's going to oxidize and turn black.

By burying copper-bearing clays in activated carbon, the metal is protected from oxygen and therefore from oxidation during the firing process. Certain types of activated carbon are used for certain clays, and you'll need to be very careful where the carbon comes from because some do not work at all with metal clay. Be sure to use a carbon that has been tested for metal clay work to avoid firing failures.

Each type of carbon has certain properties, most notably, the color of the resulting metal.

Activated Carbon - Coconut: It doesn't smell like coconut, but it's made from coconut shells. This carbon gives a clean, satin finish to the metal and no patina.
Used with: Silver Alloy, Bronze, Copper clays

Activated Carbon - Coal: Derived from coal, coal-based carbon is known for the colorful satin patina it imparts to bronze clay that results from elements natural to coal.
Used with: Bronze, Copper clays (no patina on copper)

Magic Carbon: This is a special carbon that gives an antique patina to bronze and copper clay. It can be used with silver alloy clays, but will results in a slight patina that polishing away during finishing. Magic Carbon is known for its ability to fire original BRONZclay in a fraction of the normal firing time and allows copper clay to be fired at a lower temperature.
Used with: Silver Alloy, Bronze, Copper clays