No, that’s not what potters say after we hit our finger with a hammer. They’re glaze ingredients! Welcome to my post about the behind-the-scenes of glaze mixing and its challenges!
Okay so that sounds like a bit of a snooze, admittedly. But glazes are such a huge and important part of doing ceramic art. The chemistry of it can actually be quite fascinating . . . if at times frustrating. In my opinion, glazes are their own separate world demanding a considerable amount of knowledge, experimentation, and skill. Oh, and PRACTICE. In my relatively short career (I began my undergrad in 2004) I have already done literally hundreds of glaze tests. I once mixed and fired 60 tests in the hunt for a mere 6 colors.
So it was with trepidation and, I won’t lie, some amount of dread, that I embarked on the search for a set of glazes for my new studio home at The Kentucky School of Craft at Hazard Community & Technical College (HCTC).
I’m scheduled to teach several classes this fall, and I wanted a group of glazes that would allow my students lots of different options as far as color & surface texture goes. I also wanted a group of glazes that could coordinate well together if a student wanted to use more than one on a particular piece or set. I also wanted glazes that weren’t overly temperamental. Any potter can tell you horror stories of a temperamental glaze: too runny, too rough, comes out ugly unless fired precisely right, comes out ugly unless it’s applied with the exact perfect thickness, causes “blushes” on any pots next to it, bubbles, cracks, crawls . . . . yep, there are plenty of things that can go terribly, terribly wrong. In my opinion, finicky glazes have their place with professionals, but are more trouble than they’re worth in a school setting.
Now, before I go further I should mention that you can just buy ready-made glazes from ceramic supply stores. And plenty of people do, though it ends up being more expensive in the end. My school already had a considerable amount of raw materials on hand, and I have training in mixing. So off I went on a glaze recipe hunt!
Finding good glaze recipes is a lot like finding good food recipes. The best ones are often passed down heirloom style from mentors & masters, and the internet is a dubious source at best. Knowing this, I decided to take the safe route of getting my recipes from trusted sources. I pulled recipes from Ceramics Monthly, Mastering Cone 6 Glazes, and the wonderful ceramic artists Lana Wilson & Jason Bige Burnett. I had the immense pleasure of meeting them both this summer at Arrowmont. Lana is an amazing artist and educator who has written tons of helpful articles for potters. She was fond of telling us her ceramics “failure stories” at Arrowmont, which is a great help to us early career folks mucking through our first tries at things. Jason is one of the 2012-2013 Artists in Residence at Arrowmont. He has a great joie de vivre that you can see in his work. I definitely recommend checking out their art!
Really and truly experienced glaze-makers can formulate their own glazes, from scratch. Others use a formulation software. I’m no expert, nor do I own software, so I went with the “trusted source” method. Luckily, most potters share recipes freely, as we have a shared understanding of the challenges of the media. Lana, for one, has a set of recipes for download right on her website. Plus, even using the same glaze, every potter’s work will still be different. Finally, as you’ll see later, even WITH using someone else’s recipe you can still come up with different results in the kiln.
All of those containers you see lined up are full of raw glaze ingredients. Pretty much every ingredient comes in the form of a fine powder. Most are white or tan but if you look you can spot some red or black ones. Chrome Oxide is a bright, Oscar The Grouch green. I always have to wear a respirator to work with them. The bags on the left are what most powders usually come in, then I transfer some to the containers. On the tabletop on the right are my triple-beam balance and digital gram scale. Those funky white pipes are part of the room’s ventilation.
So I went to work, mixing and testing. Ultimately, I fired two batches of tests. I wanted to try the same glazes in two different kiln programs, because the speed at which the kiln heats and cools can affect the results dramatically. Annnnnnd . . . here are the results!
I know this may not look like much, but it’s the result of nearly two months of hard work. The names of these glazes are:
(top row): Slate Blue, Caribbean Blue, Spearmint, Tenmoku Brown, Gunmetal Black (bottom row): G1214Z Matte Clear, White Satin, Kate the Younger Clear Gloss, Raspberry, Nutmeg.
I wish you could see & touch these in person because the surface textures just came out delicious. I did have a few results that came out different than what they were meant to look like, but I am actually happy with the results the way they are. The biggest head scratcher was the “Spearmint” from Mastering Cone 6 Glazes. It’s the center upper tile. It’s meant to look like this. What I actually got was a kind of yellowish leafy green color.
Turns out, the authors have an FAQ on their website addressing this very issue. One of the ingredients they used is kind of a wild card: it’s called Rutile. Rutile is a less pure form of Titanium Dioxide. It’s actually the stuff that’s responsible for the starburst effect inside of star rubies and sapphires like the famed Star of India. Because rutile is not that pure, it differs from sample to sample. I knew about this from my undergrad years when we had a glaze go “rogue” once because a new batch of rutile caused the color to shift. Mystery solved!
So there you have it, a glimpse into glaze making in all its crazy glory. Hope you enjoyed!