Firing Copper Clay

There are several brands of copper clay on the market. When I produced my Enameling on Copper Clay video back in 2014 I focused on just two, Art Clay Copper and Metal Adventures COPPRclay.   I really put them to the test and they had remarkably different firing requirements in order to successfully enamel.

ART CLAY COPPER

One of the advantages of Art Clay Copper is the ability to be fired without carbon.   That said, if I am NOT going to enamel it, I still recommend carbon firing as it eliminates the need for pickle and preserves the most amount of surface detail.   If you are going to enamel it however, carbon firing can lead to bubbling and chipping in the enamels.  

Firing for pieces NOT to be enameled

  • Put about 1” of Premium Coconut Carbon in your firing vessel
  • Place pieces face down on carbon and cover with another ½” of carbon.  Pieces should be completely covered, no copper showing, but not buried too deeply.
  • Use a vented lid on your firing vessel and place the vessel on short kiln posts inside your kiln.  Avoid getting the vessel too close to the thermocouple as that can throw off firing temperatures.
  • Firing Schedule
    • Ramp Speed 4 (1500F/815C per hour) – For very thick pieces more than 2mm thick, slow that down to Ramp Speed 3 (1000F/538C per hour)
    • Temperature 1800F/982C
    • Hold 1.5 Hours
    • Cool completely in carbon

Firing pieces to be enameled

Open shelf, no carbon firing is required for Art Clay Copper (ACC) if you are going to enamel it. Carbon methods result in bubbling and chipping of the enamel.   Do not attempt a 2-phase binder burnout/carbon firing with ACC. It will result in the piece cracking.

The way I set up my kiln is not exactly how you may have seen this described elsewhere, but I’ve found it greatly reduces the amount of fire scale you have to deal with.  

  • Place kiln posts to support kiln shelf in kiln but do not put the shelf in the kiln at this time.
  • Pre-heat kiln to 1780F/971C
  • Set up kiln shelf outside of kiln.  
    • Place a piece of fiber paper on the shelf
    • Place a piece of fiber blanket on the fiber paper
    • Place pieces face down on fiber blanket
    • Top with another piece of fiber blanket. 
  • When the kiln is hot, place the entire shelf, with the pieces already in place as described above, in the kiln.   Long tongs or 18” Reptile Feeders work well for this. 
  • Fire for 35 minutes.
  • While firing, fill a bucket of water and place it near the kiln.
  • When the timer goes off, use the long tongs to remove the shelf from the kiln.  Slide the top half of the tongs UNDER the fiber blanket so it’s not trapped.   
  • Dump the entire contents of the shelf, pieces AND fiber blanket into the bucket. 
  • After you get the pieces out, try chipping off any remaining fire scale with a metal pick.  Sometimes you can avoid pickle all together.  If necessary, use pickle to finish cleaning the piece.
  • Soak in a warm mixture of water and ammonia (about half and half) for about 10 to 20 minutes to neutralize the piece before proceeding with enameling.

I this all sounds convoluted, but this method results in the least amount of fire scale on the pieces and the best results for enameling on Art Clay Copper.  

COPPRclay

Firing for pieces NOT to be enameled

  • Put about 1” of Premium Coconut Carbon in your firing vessel
  • Place pieces face down on carbon and cover with another ½” of carbon.  Pieces should be completely covered, no copper showing, but not buried too deeply.
  • Use a vented lid on your firing vessel and place the vessel on short kiln posts inside your kiln.  Avoid getting the vessel too close to the thermocouple as that can throw off firing temperatures.
  • Firing Schedule
    • Ramp Speed 4 (1500F/815C per hour) – For very thick pieces more than 2mm thick, slow that down to Ramp Speed 3 (1000F/538C per hour)
    • Temperature 1800F/982C
    • Hold 3 Hours
    • Cool completely in carbon

Firing pieces to be enameled

A 2-phase firing is needed for pieces that are going to be enameled.  Failure to use the two phase firing can result in enamels bubbling and chipping.  

  • PHASE 1 – Binder Burnout
    • OPEN SHELF
    • Ramp Speed 2 (500F/260C per hour)
    • Temperature 560F/293C
    • Hold 15 minutes.
    • No cool-down period needed
    • PHASE 2 – Carbon Firing
      • Carefully transfer pieces to carbon as described in previous carbon firing instructions
      • Ramp Speed 4 (1500F/815C per hour) – For very thick pieces more than 2mm thick, slow that down to Ramp Speed 3 (1000F/538C per hour)
      • Temperature 1800F/982C
      • Hold 2 Hours
      • Cool completely in carbon
      • No pickle required.
      • Soak in a warm mixture of water and ammonia (about half and half) for about 10 to 20 minutes to neutralize the piece before proceeding with enameling.

 

 

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