Stone Mountain Clay & Glaze Co.

4744F North Royal Atlanta Drive
Tucker, GA  30084
PHONE (770) 986-9011 / FAX (404) 492-7190
Yes, we are open to the public! 

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335 Onyx Krunch Stnwr.

335 Onyx Krunch Stoneware is our newest clay. Onyx Krunch is jet black in color, when fired to Cone 6, and has a great crunchy texture for larger thrown, handbuilt and sculptural pieces. 335 is ideal for slabs and tiles, takes attachments without difficulty. 335 vitrifies (becomes water-tight) at Cone 6, and should only be fired to Cone 6 oxidation (never in reduction). We strongly recommend a Cone 04 bisque-firing with the Onyx Krunch Stoneware.

The key to success with 333 Black Raven Stoneware and 335 Onyx Krunch Stoneware is a slow firing to a straight cone 6. Firing too quickly, or firing too cool during the bisque can cause problems during the glaze firing (bloats and blisters). DO NOT reach cone 6 and hold temperature for any length of time. This increases the heat in the clay and can cause blisters and bloats. If you are using a programmable kiln, we recommend the slow bisque setting to cone 04 and the slow glaze setting to cone 6. All our our stonewares can be fired with the same program, in the same kiln, as the black stonewares. Follow those programs, or our firing chart for sitter/timer kilns, and you will experience the best performance from these gorgeous clays!

Attention Skutt Kiln users: If you have a newer model Skutt, that does NOT feature the Bartlett V6-CF controller, you may experience some bloating with Black Raven and other dark or speckled stonewares when using the slow program. Their newer kilns feature a controller that does not let you select between a bisque and a glaze profile, and therefor does not fire quite the same as other computerized kilns.  This may not impact your firing with lighter-colored bodies, but it often does with darker bodies. Their slow profile for cone 6 unfortunately fires almost twice as long as other controllers.

If you have this newer controller, we recommend that you continue to use the slow cone 04 profile for bisque in your Skutt, and test firing with the MEDIUM cone 6 program for glaze. This has proved very successful for many of our customers. The other option is to download and use the slow bisque and slow glaze firing profiles from the Bartlett website here:

With a typical slow firing, your bisque should last approximately 10-12 hours, and glaze firing should last approximately 7-9 hours. If you are experiencing odd firing results or noting times that are drastically different from these recommendations - please call us so that we can help figure out what's happening with your firing, and ensure the best possible results.

Its jet black color typically alters a glaze's fired color, sometimes drastically. We can make many glazing recommendations, and always recommend you make test samples when using Onyx Krunch with new colors. 335 is wonderful to use with slips, such as porcelain or red, as it can create a striking glaze contrast within your design.  Uncomfortable selecting glazes for the 335 Onyx Krunch? Check out our "Black-Tie Affair" glaze sample pack, featuring ideal glazes for this dynamic clay body.

Did you know...Using a clear Cone 6 glaze on the Onyx Krunch will not give you a shiny black pot, instead your piece will be shiny brownish-green. If you wish to achieve a glossy black finish, we recommend our #407 Buttered Popcorn glaze.

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