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Glaze Chemistry

Remember, in high school chemistry class when you found yourself thinking, “when will I ever use this stuff in my life?” (unless, of course, you always dreamed of becoming a chemist). Well, once you have become hooked on pottery and ceramics, you will probably find yourself delving into glaze chemistry. Learning how different materials contribute to glazes and clay bodies is very important in expanding your abilities as a ceramic artist. So here we’ve gathered a bunch of articles and information on glaze chemistry to help you understand this incredibly complex and fascinating subject. 33 Tried and True Glaze Recipes, a perfect resource for potters and ceramic artists who are ready to experiment with custom glazes, or for those who have grown tired of their own tried and true glazes.


Leaving Bariumville: Replacing Barium Carbonate in Cone 10 Glazes

Posted On November 17, 2009 5 Comments

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.


The Many Faces of Iron: An Exploration in Cooling

Posted On November 16, 2009 4 Comments

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.

gloss-blue-glaze by Jeff Zamek

Glazes: Materials, Mixing, Testing, Firing

Posted On November 5, 2009 4 Comments

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.

The tiles above are examples of a single glaze base (Turner’s White) used to obtain a variety of colors by adding coloring oxides. The top row was fired to cone 6 electric and the bottom row to cone 10 reduction in a gas kiln.

It Slices, It Dices! Some Simple Glaze Tests Reveal a Ceramic Glaze That Can Do it All (well, almost)

Posted On October 26, 2009 11 Comments

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.

Panama Red Glaze, Cone 6 reduction

Mid-Range Reduction Firing: It’s Not Just Cooler, It’s Cool!

Posted On May 13, 2009 20 Comments

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.

Test glazes, each consisting of 8 parts Sumi's Volumetric Clear to 1 part Mason stain. Back row, left to right: stain 6319 (Lavender), 6364 (Turquoise) and 6387 (Mulberry). Front row, left to right: stain 6000 (Shell Pink), 6407 (Marigold), 6121 (Saturn Orange) and 6006 (Deep Crimson). Tests are on cones made from slabs rolled out on lace to show how the glaze looks on a textured surface.

No Scale? No Problem. Using a Volumetric Glaze Recipe for Ceramic Glaze Testing

Posted On February 2, 2009 1 Comment

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.


Expand Your Ceramic Glaze Palette, Part II

Posted On October 15, 2008 1 Comment

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!

This image shows the fired result of mixing the green and white glazes shown on the plates below right.

Expand Your Ceramic Glaze Palette, Part 1

Posted On October 13, 2008 8 Comments

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.