The following procedure should be followed carefully to avoid cracking:
Parts with cross sections exceedíng 1/2" are more critical and cracking may occur during the firing cycle. If a cross section of 1/2" or greater is unavoidable, a heating rate of approximately 50°- 150° F per hour and strategically placed stress relief holes may help minimize cracking.
The maturing temperature of Grade “A” Lava is between'1850° and 2000° F, The temperature should be maintained for approximately 30 minutes up to 1/4" cross çectìon and 45 minutes for 1/2“ and greater cross sections. Fired pieces may be removed from the furnace after cooling below 200° F.
During the firing process, Grade "A" Lava expands approximately 2%. A Temperature of 2000° F should not be exceeded. If 2000° F is exceeded, crystallization, distortion, shrinkage and a loss of stated material properties will occur.
As with most natural materials, texture, color, hardness, machinability, final expansion, and ideal firing temperatures may vary.
Please feel free to contact our technical staff with any additional questions that you may have.