With the new kiln, a Paragon SC2, I’ve been stock piling my bronze pieces so I could fire one large load. Somewhat a success, but I did loose two pieces, both of which seemed to pull apart/break at a narrow point. Maybe due to shrinkage factor.
This batch was made with Fast Fire Bronzclay. The focus was on getting the firing schedule right. There were a variety of thicknesses, shapes, and designs. All pieces were air dried for three days and fired in the SC2 kiln. I did a full ramp to 1525, held for 2 hours and 25 minutes and left to cool over night. It was not fully cooled by early morning so I carefully removed them to a water bath. I used a lid on the stainless container and used Magic Carbon.
I’ve discovered with earlier firings, that the bronze has a distinct ring when if fully sintered, as it hits the counter. All pieces except two had that ring. I’m not sure if it is because they are not solid pieces or if the thickness where clay overlaps has not sintered. I plan to fire them again to be sure they are ready.
You can see the pieces that separated or broke on the far right. Next step is polishing and cleaning.
I’m thinking there were three big mistakes. 1) firing with lid on container; 2) prolonged cool period; 3) order items were placed in container. Will be seeking other’s advice.