Glazing Mugs, Plates, and Lemon Squeezers

My kid's reaction to a calendar snafu on the first day of online school

I was able to bisque and glaze almost a full kiln last week. Studio work this summer been slow, but work has gotten done. I used up all my porcelain clay and ordered more about a month ago. I ordered it from Tacoma and they sent it USPS to a different address in Yakima. Strangely they sent the other stuff I ordered to my house. Then they had to send they back to Tacoma before sending it back to Yakima for me. 50lbs of the clay made it to my house a week or two ago. The other 50lbs appear to be trapped in the USPS black hole. The clay has left Tacoma, but the tracking doesn't identify any more movement. I assume no one at USPS wants to pick up this 50lb box during the chaos and I don't blame them. 

bisque ware waiting to be glazed, mugs, plates, citrus squeezers and bulbs

Because I used different temperature clay for different projects, I wasn't able to fire the bulbs in the same firing as the plates, mugs, and citrus squeezers, so those haven't gotten done. I keep thinking I will make time to throw some more so I can fill a kiln to fire the mugs and bulbs I finished after this last firing, but I haven't done it yet. Instead I'm working on online classes, doing union stuff, and procrastinating. Today, I am also trying to calm down my kid, whose reaction to online school has been stomping, crying, and generally freaking out. First there was an error in the timing of the first class, then the link to the second class doesn't work. After solving the first issue, she allowed up to 12 minutes for her teacher to help on the second, but just in case he didn't reply, she started freaking out immediately. Um, so my hope for the school year is that this 7th grader learns patience?

porcelain plates from the second firing, and one stoneware clay on the top right

I'm pretty happy with the plates from this batch. In the first round my glaze application was irregular on some, and because I was worried about glazes dripping in the kiln, I put the plates on stilts. This was a dumb solution, because not only did I not put enough glaze on to drip, making the plates look a little splotchy, firing on stilts also warped the plates. This time around I used more glaze and did not stilt the plates, so there's less splotchiness and all the plates are flat and even.

porcelain plates in yellow, pink and peach

I also changed the shape for most of these plates because they were done on request. The person who ordered them wanted small plates with a flat flared rim. She liked them, so three of the six porcelain plates have been sold since I took these pictures. Four of the plates were done in a groggy sculpture clay, which is serviceable, but mutes the glaze colors and doesn't look as nice.

On all the plates I drizzled other colors inside. The reds and a sparkly glaze look particularly nice in person, but the photos didn't capture the colors as well.

I also glazed three screaming face mugs I made with the porcelain clay. I used dark glazes to highlight the features and wrinkles, and a semi-transparent glaze for the entire exterior. I am not excited about the result. The faces look too white and too plain. Part of the problem is the limited number of glazes I had (partly because I used some up on the plates) and part of the problem is that I didn't leave enough of the dark glazes in the wrinkles and indents. I have ordered some new glazes so on the next batch I can bring more color, assuming the glazes also don't end up in USPS limbo.

My kid's reaction to an error in a Google Meet link on the first day of school

I think these faces would look better if I layered more colors. I usually do this with my underglazed sculpture, putting down a base coat on bisque ware before a second firing, then layering a wash of contrasting color over the first. I haven't tried that with these glazes, but I'm considering it. Underglazes and glazes handle differently, but it's worth a shot.

screaming face mug with minimal color in the eyes and eyebrows

I did minimal mixing of colors in these mugs, but I was tentative compared to my "usual" work. I also did some mixing/layering in the new lemon squeezers, but for some reason the yellow and blue showed up best and overwhelm the other colors (or maybe I forgot to use much other than blue and yellow). I know I used the red/pink on at least two pieces and now it is barely evident.

 

most of the citrus squeezers from the second batch, in both porcelain and sculpture clay

Something else happened in the glaze firing for these citrus squeezers. And this requires a bit of back-story. When I was in college, my clay professor told us that anytime we had a contained air pocket, it needed to be pierced so that the air could escape. If not, it would risk blowing up in the kiln. This is pretty conventional wisdom in the clay world and I know I've repeated it often enough. I remember one instance when I remembered too late that I had forgotten to pierce an air hole in a piece. When I opened the kiln I was surprised to see the piece had not exploded. At the time, my professor and I guessed that it was because I was using a raku clay, which is more porous than other clays.

more blue and yellow squeezers

Many years later, I joined a clay community on Facebook. One of the regular topics that comes up over and over again is that air pockets don't cause explosions during firing, only wet clay does. The reasoning goes that air is so small that it either doesn't need to escape or escapes through the walls of the clay. I allowed students to test this theory in class. Usually the pieces didn't explode, but sometimes they did. When asked, the folks in this online clay community assumed that these students must have soaked the pieces before glazing, or the pieces were simply too thick, or there was unaccounted for moisture left even after a long candle (candle means preheating the kiln to drive out excess moisture) or long drying time.

the bottoms of these two squeezers expanded due to expanding air inside during firing

It's difficult to rule out all these options with student work, but the results seemed inconclusive. This still bugs me, so I periodically test the theory. In my first citrus squeezers, I pierced the forms, leaving an unnecessary/essential escape for any heated air. This time around I did not pierce the forms. None of the pieces exploded in either firing, but in the glaze firing the bottoms of two of the pieces, which I had set on stilts in the kiln, expanded during the firing, going from a slightly concave base to a slightly convex base. Meaning that an air pocket inside did, in fact, expand during the firing and was unable to escape, suggesting that my online clay community, despite regular repetitions, is incorrect on this topic.

Student Sculpture from Winter 2017

This reclining lady, whose body and face are covered with leaves, is actually incomplete, according to the student, and may have more color when next seen at the DoVA Student Exhibition in May.

Last week was finals for winter quarter at Yakima Valley College. I had four clay classes, two of which were hand-building classes, the others were wheel classes. We had glaze critiques for both groups and I remembered to take pictures of some of the work that was finished. 

 

These two portrait heads were some of the last pieces finished building, but both survived with minimals cracking during the firing.

The end of a hand-building class is fun because we get to see such a wide range of work. This quarter I began the class with a portrait project. It was fun to start this way, but the project was more challenging than my usual beginning project using coils. The class, overall, did fairly well building the portraits, but we encountered more trouble* with thickness, air pockets, and cracks or blow-ups during firing than usual.

  

These three heads show the range of damage: the grey lady's chin and mouth hid an air pocket which exploded during the firing, taking of her chin, but also cracking her head from her shoulders, Dwight from The Office had less extensive damage, most of which was repair before critique, Kanye was well crafted and very thin so that he survived the firing with not even a superficial crack in his head or body.

The higher than usual breakage may have been because we started with such a challenging project and the students didn't fully understand why the pieces had to be as thin and I told them or it may have been because they had trouble making the pieces as thin as I instructed. Many, though not all, of the sculptures had to have some sort of repair done after firing to deal with cracks, exploded parts, or parts that broke off before or during firing.

 

These two very different approaches to dog portraits were also finished very differently; the one sitting up was painted with underglaze and some low fire glaze and fired, the one on the left was painted with acrylics.

During the last weeks of the quarter, I gave several epoxy demonstrations to show students how to repair cracks or breakage, smooth seams, and fill gaps left by the explosions. I demonstrated three types of two part epoxies: some simply two-ton epoxy gel, some PC-11 epoxy paste, and some epoxy putty for filling gaps. I also demonstrated and discussed how to hide or fill cracks, make the epoxy less visible, and match the glaze color and texture with paint and gloss medium.

This cat is hard to photograph because of its shiny black glaze, but the form is interesting in person.

Despite several demonstrations and explanations, a significant portion of the class had trouble understanding that epoxy and acrylic paint cannot be fired with glaze in the kiln. I eventually started keeping count of how many times I had to repeat the explanation or reminder that epoxy will burn off in the kiln (I repeated it 9 times, though, to be fair, the last several reminders were to individuals).

This small portrait suffered from an unexpected underglaze reaction that turned the face bubbly and rough and perhaps darkens the character, but the expression is still effective.

I am actually a bit concerned that so many of the students seemed not to grasp the basic physics of firing and the processes that impact shrinkage, glaze melting, and the process of turning clay into ceramic, not to mention the difference between clay and epoxy, paint and glaze. I feel that I spend a significant amount of time talking about not just what students need to do to keep their sculpture intact, but why. I'm considering, next time I teach this class, firing a sacrificial piece in the kiln to show them what happens with epoxy. I may also switch the assignment order back to what it had been--easier project first.

This peacock meant to hang on the wall survived building, firing, and glazing, only to suffer damage from rough handling on the day of the critique. The break is minimal, however, and the peacock should show up in the Spring DoVA show.

Because of the structure of the 10-week class, much of the work is not completely finished until the last week. The first three projects in the class are building projects which we critique when the work is wet, dry, or bisque fired. The final critique is a glazing and finishing critique, in which we see the first three projects again, this time with glazed and/or painted surfaces.

 

One challenge of photographing in the classroom without a photo setup is that some of the angles don't show the full sculpture. This carefully repaired and painted elephant has an interesting pose from multiple perspectives.

The good thing about this setup is that the students get lots of time to start glazing their first and second pieces. The bad thing about this setup is that students sometimes run out of energy and enthusiasm at the end of the quarter, meaning that sometimes glazing on well-built projects is poorly executed. 

This elephant, too, suffers from the poor quality photo, but his extensive repair was particularly well done.

This quarter I had one student, in particular, who had two well-built projects with poorly executed glaze. The glaze on one was so thick it ran extensively, permanently attaching her sculpture to a biscuit of clay placed underneath to prevent damage to my kiln shelf. Another of this student's pieces had very thin glaze that ended up obscuring the texture of her sculpture rather than highlighting it. 

These two sculptures are actually pieces of three separate works that were damaged during firing. The end-result combines  raku and cone 10 reduction firings, as well as epoxy.

However, I also had one student who managed to resurrect some sculpture that had been almost a total loss because of an explosion during firing. This student's work had lots of damage during firings, but he spent time carefully applying epoxy and paint to repair one piece in such a way that the damage was hard to see at the critique. He also brought several broken parts of other works together with various glaze applications to create a new sculpture. 

This mermaid platter was painted with underglaze but not glaze for critique. The photo angle doesn't really show the depth of the piece.

It's lots of fun to see the stuff students finish, especially when they take the time to make the repairs, but it's disappointing when students don't finish their work. Similarly, it is disappointing to grade that last test and realize that they never did understand a fundamental concept from the class. Last week I had a few of these disappointments, but I also had a few of the best grading experiences: when the last test was better than all the previous tests, or when the discussion at the class critique revealed that the student knew their glazes and could explain exactly what they did to achieve a certain visual effect.

A tree with blue snake and a totem pole with a blue snake.

* The basic rules for a safe bisque firing are to make sure that the work is dry, make sure it isn't too thick (I usually tell students to aim for a quarter to a half inch or no thicker than their thumb), make sure there are no contained air pockets (because hot air is bigger than cool air), and make sure to fire the kiln slowly (with a preheat or candle). Most, if not all, of the cracking this quarter was due to thick walls and/or contained air pockets that exploded.

This poor turtle suffered from air pockets and thick walls.