How I fixed the pinholes in my chocolate pots
I am a novice potter. I first got the bug to start throwing pots watching Great Pottery Throwdown bootlegs on Youtube while I was recovering from gallbladder surgery in the summer of 2019. I took my first pottery class in October of 2020, and somehow in just over a year, I have a basement studio that I share with 2 friends. We have 2 kilns, 3 wheels, and more glaze than any novice potter should have access to.
I’m also a veterinarian, an engineer, an educator, and a scientist, and I’ve spent the last 30 years of my life developing and leaning into my left brain. But one of the few positive aspects of the disaster that was 2020 was less time traveling and more time to actually recognize that I have a right brain as well. An artistic side and a desire to create things without utility other than their aesthetic value. And so I throw pots with limited skill but great enthusiasm. I taught myself how to fire a kiln, how to mix glazes and porcelain slips, and how to install a drain for a utility sink in the basement. Immersing myself in something for which there is no right answer, just endless opportunities to create and explore has been challenging, exciting, and surprisingly fulfilling.
So what’s a pithole? It’s a defect in the glaze surface that continues all the way down to the underlying clay. For functional pieces that will be used for food or drink it’s problematic because moisture and organic material can get lodged and lead to bacterial growth that could be harmful to the person using the piece. I made a few pieces with a particularly problematic but very pretty chocolate clay for a fundraiser for a group I follow (I have a pathologic attachment to Irish Wolfhounds), and the ones I made with the chocolate clay had horrible pitholing (see the yellow arrows). So my engineer brain kicked in and I decided I was going to fix it.
It turns out, pitholing happens because organic compounds in the clay burn off during the glaze firing and bubble through the melted glaze. If that’s happening while the glaze is cooling down and solidifying, the bubbles turn into pitholes. And there were lots. So how does the artist solve this issue? He turns to science (and, of course the internet). It turns out that this annoying issue can be fixed in a programmable kiln (which I happen to have in the basement) by doing a “drop and hold” firing. Basically you heat the kiln up as usual to get the glaze to melt, hold it there for 5 minutes, then drop the temperature a bit and hold it there for 30 minutes. During that time, those organic compounds burn off and bubble out, but since the glaze is still melted, it can “heal.” I was dubious. I’m kind of a “show me” guy, and there is no way to look into the kiln to watch this happen. But I wanted to salvage the pieces and decided that the theory made sense, so it was time for an experiment. And wouldn’t you know it, it worked!
So why did I make this my first blog post? And why am I blogging at all? For me, this was a mashup of my long time left-brain predominance starting to show me its value in my new right-brain focus. Science and art. Maybe they’re not in opposition, and clearly they both make me, me. And they let me make really cool pots that bring me, and hopefully others, joy. And will raise a little money for a group I care about.
I don’t know if anyone will actually read this, but it’s helped me explore the gratitude I feel for finding a new creative outlet in the face of a very tough year. Maybe someone else out there will find some joy in reading about it too.
