Barium carbonate has long been used as an ingredient in high-fire glazes, sometimes conferring unique properties upon glazes. One of the alkaline earth carbonates, it has also been used as rat poison (large doses can be toxic to humans as well). Glazes containing it ought to be checked for barium leaching if they are intended to hold food or drink, or reserved for surfaces that do not come into contact with food. It is not my intent to present the research on barium toxicity here, but to present a course of action for replacing it in glazes.
One of the more fascinating, sometimes frustrating parts of ceramics is learning to balance the innumerable factors that affect the outcome of a firing. Glaze ingredients, the clay body used, firing cycles, atmospheres, kiln-stacking techniques and geography (to name a few variables) can all affect firing results.
How many times have you copied a glaze formula, only to find that it didn’t work as expected? It is not unheard of for glazes with the same formula to produce different results. While this may seem like a dead end, it does not have to be.
It Slices, It Dices! Some Simple Glaze Tests Reveal a Ceramic Glaze That Can Do it All (well, almost)
Kristina Bogdanov, who teaches at Ohio Wesleyan College in Delaware, Ohio, was intrigued when she realized that one of the class glazes seemed to fire well at cone 10 reduction in a gas kiln, cone 6 in an electric kiln, and cone 9 reduction in a soda kiln without any change in the recipe. So she ran the glaze through a battery of tests to see just how versatile it was. Today, in an excerpt from the 2010 Buyers Guide for Ceramic Arts, Kristina explains her testing process and the results.
As John Britt points out in today’s post, firing to cone 6 reduction is cheaper, faster, and the results can be almost indistinguishable from high fire.
Mixing ceramic glazes from scratch can be intimidating to those just getting started. And sometimes it just isn’t practical or possible to purchase or have access to an accurate gram scale. But that doesn’t necessarily mean that mixing glazes is out of the question. As Sumi Von Dassow explains in today’s post, mixing ceramic glazes with a volumetric recipe can be a great way to get your feet wet and learn more about ceramic glaze materials in the process. – Jennifer Harnetty, editor.
On Monday, we presented a couple of ways that you can expand your glaze palette without purchasing new materials or experimenting with new glaze recipes. If you missed that tip, you can see it in the online archives (along with every other feature we’ve published—just click on “Features Archive”).
As promised, today, Lou Roess shares another handy tip for getting a lot more information out of the glazes you already have. You may discover something new and interesting right in your own studio!
f you’d like a bigger selection of glaze colors, but don’t have the time or money it takes to mix and test new ones, don’t fret. Working with what you have on hand can yield some interesting results. Today, we’ll show you a couple of simple ways to get more from your studio glazes.
Whether you mix your own glazes, use commercial glazes or both, it’s easy to get comfortable using the same glazes the same way on the same pieces. That’s not necessarily bad, because being comfortable with your methods builds confidence and consistency. However, it’s also wise to experiment and stretch a little bit to discover new territory. The methods below show that new territory might not be that far away. Wednesday, we’ll follow up with another method.