The recent crystal firing presented both surprises and learning opportunities. Two crystal pieces showcased larger crystal formations. We experimented with a new firing schedule, which could be one reason why some crystals did not form—another possible factor being insufficient glaze application. Our members’ pieces had a failure to launch, some variables include the Clay body used. I typically employ Cinco Blanco, a cone 5/6 clay body by Armadillo Clay in Austin, TX. In contrast, other members used reclaimed clay and a buff cone 10 clay body.
One of the partially successful glazes I tested in this session was the cone 9 crystal base recipe #11, which incorporated black copper oxide, lithium carbonate, and cobalt carbonate. It appeared that these pieces were not glazed heavily enough.
On the angular lamp base pictured above, some crystals formed effectively where the glaze was most generously applied, allowing a thick enough layer for the crystals to develop. On another altered thrown form, smaller, incomplete crystals appeared on the upper band where the glaze was thickest. Crystals also formed at the base of the piece, where the glaze accumulated and in the dips of the form, creating a small river of crystals that crested over the form like a miniature waterfall.
Crystal Glaze Successes
Two of the pieces that exhibited the most impressive crystal growth came from a recipe I discovered on Glazy. The glaze features a pale yet vibrant green background with crystals that have a metallic bronze tone. My personal favorite is a small vase with the same green backdrop but with subtle variations in the light and dark spots where microcrystals begin to resemble moss and lichens on rocks. The bronze, almost splotchy crystals give off an antique vibe. My favorite detail is the center of a crystal formation that resembles a flower with a leaf and stem.
Lessons Learned
This time, we strategically employed cookies and seashells to protect the kiln shelves and minimize glaze runoff—though not without some challenges. As you can see in the picture, our efforts were somewhat successful, but the kiln shelves still endured a bit of wear. Fortunately, thanks to our use of kiln wash and a bit of diligent work with an angle grinder, we managed to clean them up nicely.
Now, let’s discuss the lessons learned and the measures we plan to implement to prevent similar issues in the future. One major adjustment will be making larger cookies or catchers to better handle the glaze runoff and shield our kiln shelves more effectively. This adjustment should help us maintain the integrity of our shelves and improve the overall results of our firings.
All in all, it was a great learning experience, and we are excited to continue exploring, testing, and learning new things. Each firing brings its own set of challenges and discoveries, fueling our passion for ceramics and enriching our collective expertise. We look forward to more experiments and sharing our findings with the community as we further our craft!
See you at the next Crystal Lab
-Trey Morgan
P.S. Want to take a class and learn more about glazing check out our Glaze Class