Prometheus Clay - Working Tips

If you've never worked with Prometheus® metal clay before, you're in luck! We have a ton of tips and tricks for this versatile material from Prometheus®.

Clay Working:

• When the clay comes out of the package, it is drier than you may want to work with. Recondition it with water as you would with other clays. It holds the water better than most clays and will keep a perfect condition longer.
• Prometheus clays are very dense. Make sure to let the pieces dry completely before firing. This can be a little longer than other clays you have used. You may want to ''flip'' the piece over on each side to let the surface dry. This helps to prevent cracks while the clay shrinks during drying and is especially beneficial if you are using a heated surface to dry the piece rapidly.
• It is helpful to sand the piece all over during the refining phase. Since the clay is so dense, the surface area will actually polish during the refining phase and be shiny like metal. This will help you achieve a shine even prior to polishing.

Firing:

There are several options to fire Prometheus metal clays. Be sure to read each option carefully.

It is best to complete the burn-off stage slowly working from one end of the piece to the other. If performed in a kiln, a burn-off without carbon is recommended. This complete burn-off of the binders is critical as full sintering will not occur unless all binders have been removed.

Torch Firing:

• Prometheus Copper and Bronze clays can be torch fired. Prometheus White Bronze clay cannot be torch fired.
• Torch firing is recommended for pieces about the size of a quarter and no thicker than 1/4''.
• The correct color to look for is based on the metal type. Yellow is too hot (high) for either metal. If you fire the piece too hot it will be blistery and have significant cracks.

• Bronze should be torch fired around 1500°F which is a cherry red color.
• Copper should be torch fired around 1700°F which is an orange color.

• Your firing time will be about seven minutes, longer for thick pieces.
  
• Signs that sintering is complete:

• Your piece will lay down flat on the firing surface
• You may see small pin points of bright orange inside your piece

• Quench the piece in water while it is still red hot. If possible, keep the flame on the piece until you place it in the water. This will help remove some of the oxidation (black residue).
  
• Check to make sure the piece is sintered by hitting it with a piece of metal or tapping it on the table. If it ''clinks'' it is sintered. If it 'thunks'' it is not finished and you should fire again.
  

Kiln Firing:

• There are several options for kiln firing. Please see the complete instructions inside the package for the standard firing practices.
• In addition to the standard firing practices in the package, a paper towel package method has also proven very successful when working with Prometheus Copper and Bronze clays.

• The paper towel package method - Use approximately 1/4 sheet of paper towel. Lay about a tablespoon of carbon in the center of the paper towel. Put the dry piece on top of the carbon. Lay another tablespoon of carbon on top of the piece. Carefully wrap the package so that the carbon is surrounding the entire piece. Lay the package on a fire proof surface such as a ceramic or fiber shelf. Put into a pre-heated kiln (Bronze 1500°F and Copper 1700°F). Fire for 30 - 45 minutes. Quench while still hot to remove excess fire scale 




         Note: This method is not recommended for Prometheus White Bronze clay.