Monday, December 29, 2014

Mugs Out of the Kiln

I pulled some glazed mugs out of the kiln the other day. I taped them with two kinds of tape resist during the holiday break. I glazed them with mostly two colors of low temperature glaze and clear glaze over the tape resist lines. 

The resist results are better on the pieces on which I used the better tape, something I knew before I fired the pieces. The glaze results are better on the pieces where I used just one glaze and the clear over the top after I removed the tape.

On several others, I sprayed a second colored glaze over the top after the tape was removed. These pieces are less bold, though they have some more subtle color variation.

After these pieces came out, I glazed some plates I had thrown during the break. I used mostly one colored glaze and the clear over the top to replicate the results with more contrast.

Friday, December 26, 2014


I've fired several kiln loads of work over the past few weeks. These loads have consisted mostly of small pieces with no base and therefore no logical ending place for the glaze. When I apply glaze on all sides, I need to stilt each piece so that the glaze won't melt and stick the piece to the shelf. 

stilted pieces in the kiln after firing

Most of my shelves have kiln wash on them, meaning they've been coated with a layer of material that keeps glaze from sticking to the shelf. If I were to get glaze on the bottom of a piece, the glaze would melt, stick to the kiln wash and later lift off the shelf easily with a bit of kiln wash on the bottom.
checking the fit of the stilt before loading into the kiln

If I put glaze on the bottom of a piece that is loaded on an un "washed" shelf, the glaze will melt, sticking the piece to the shelf. Removing the will take a bit more effort, and may result in part of the piece sticking to the shelf and breaking away from the piece, or vise versa. Glaze on an unwashed shelf usually results in damage to the piece or the shelf.

four point metal "jacks" stilts and a variety of ceramic stilts with metal points

To prevent damage to the piece from kiln wash and to prevent damage to my unwashed shelf, I load these small, bottomless pieces on stilts. I have a wide array of stilts, including metal pointed stilts with three or four prongs and some four-pointed metal stilts that look a bit like jacks. I can arrange pieces so that they each have a stilt or two or three. More points of contact between the stilt points and the piece makes the piece more stable and less likely to tip off the stilt during loading or firing.

the white spot is where the glaze melted to the shelf after this piece rolled of its stilt during firing or loading

After firing, the glaze has melted, but, assuming the glaze hasn't run down past the point of the stilt, the metal leaves a tiny hole in the glaze that is more or less invisible. If you look carefully at "China" dishes that have a shiny surface inside and on the foot, you can see three or four tiny holes in the glaze on the bottom. These holes are the marks of the stilts used to hold up the pot in the kiln. If your dishes have a matte surface on the bottom, but are shiny on top, they were "dry footed" during the firing and never had glaze applied to the bottom so that it wouldn't melt during firing. These pieces didn't require stilts to keep them from melting during firing.

Monday, December 22, 2014

Lidded Jars, Thrown With The Lid Attached

A few months ago, a student of mine was telling me about a video she had watched in which the potter threw a lidded piece with the lid attached. In class I have often shown students how to throw "knob'n alls" that are thrown in one piece and later the lid is cut off. I first heard of these pieces on a Robin Hopper video "Form and Function."

closed top cylinders (for sculpture, not lidded containers)

I find 'knob'n alls" easy to throw, if not exactly easy to spell.  They are simply cylinders that close at the top. Later the top half of the piece is cut off, usually at an angle. The lid fits tightly because it was originally part of the piece itself. 

a knob'n all

The lid can be made to fit very tightly by keying the cut. Instead of cutting off the lid evenly all the way around, I cut a notch or notches which then help keep the lid in place and assure that the lid is always put on in the correct orientation.

new knob'n alls drying (before cutting)
When my student told me about her new method for throwing a knob'n all, I didn't really understand her. It wasn't until the quarter was almost over, and I was laying in bed thinking about throwing projects, that I really thought about what she had said. I realized what she meant and what she'd done and I determined to try it.

lid after trimming (I didn't have a chuck, so I used a glass jar)

Last week I threw some of the new knob'n alls. The piece is thrown basically the same as normal, a cylinder with a closed top, but before finishing, I pushed the wall in, just under where I wanted the lid, to create an indent. It took me a few tries to find the right shape of tool to create the indent. The indent will eventually become the lip that comes down from the lid and inserts into the base of the container, keeping the lid securely in place.

lidded container after trimming

Later, once the piece has dried a bit, the bottom edge of the indent is cut and the excess trimmed away. The lid now slides easily down into the base, creating a secure lid. I tried this method a few times and all of them worked to different extents. I learned a bit more about how thick the wall needs to be where the indent is and how deep the indent itself needs to be. I'm looking forward to sharing this with my students next quarter.

trimming base on the lidded container

Friday, December 19, 2014

Tape Lines

A while back I ran out of thin tape, the kind I used for taping lines on mugs this summer. The tape was something my husband had already. It looked like a roll of very thin blue masking tape (painter's tape) but it had a shiny surface, more like electrical tape. 

tape resist mugs (from the summer)

I went to buy some more, thinking I could find it at Ace Hardware or Lowe's but I wasn't able to find it. Since I didn't want to wait and I didn't want to drive all over town, I went to Schuck's Autoparts for car detailing tape. I got two different thicknesses, (I didn't get any flames).

auto detailing tape (resist)

I used the new tape this week and was amazed by how much easier it was to use. Other than the difference in color, it didn't look much different, but it behaved very nicely. It stayed on the surface of the pot without wanting to pull off, I could lift and restick it when I made a mistake, and I could even wrap it inside the mugs easily.

auto detailing tape applied to a bisque mug

The old stuff would act like it was in place and only later would I realize that it was pulling away from the walls because the tension was too much for it. I can't tell if the new stuff bends into place easier or has more elasticity in the tape itself, but either way, I'm glaze I have it. It took less time, and certainly was less frustrating, to apply.

auto detailing tape applied to a bisque mug

The one thing I will change next time is the color. It's hard to see the white tape on the bisque ware mug. However, once the glaze has been sprayed on, the white and the blue both show up fairly well, especially with the light colored glaze.

glaze sprayed over tape resist

I use the tape as glaze resist. I apply it to bisque fired work and then spray on the glaze over the top. The glaze doesn't stick to the clay that is masked by the tape. I can then peel off the tape, leaving a clear line of unglazed clay.

glaze sprayed over tape resist

Since I want the interior of the mug glazed for easy clean up, I can either spray clear glaze or a colored glaze over the first layer of glaze after removing the tape resist. Both colored and clear glazes interact with the initial glaze at least a little. Last time I tried this, I liked the contrasting results I go using this method.

peeling off tape resist

I can also leave the exterior unaltered and the resist lines unglazed. This simpler approach leaves the exterior with contrasting color and texture, though the difference is hard to see in a photograph.

glazed mugs after tape resist (old kind) was removed

This last glazing round, I had two types of tape on my mugs. The new tape worked very well, leaving clear distinct lines with smooth edges, especially with the reddish glaze. The old tape left wiggly edges where the glaze had leaked behind the tape, especially with the gray (Green Float) glaze, which was more watery than the red (Camel) glaze.

glazed mugs after tape resist (old on the left, new on the right) was removed

The rough edges can be cleaned up with a knife, but part of my goal in this glazing method was to add visual contrast without significantly increasing my effort level. The second type of tape was easy to apply and I didn't have to clean up the edges much, so it's the clear winner.

glazed mug after tape resist (new kind) was removed

I only have one mug from this batch out of the kiln. The rest go in Saturday. The glaze below is the reddish glaze (Camel) with clear sprayed over after the tape was removed. This mug was done with the second type of tape (the better kind), so the lines are fairly clear.

Glazed mug after this week's firing

Tuesday, December 16, 2014

Glazing and Firing a Small Batch

This is the last week of school for the district, but the college finished last week, so I got some under glazing done yesterday and some glazing done this morning. I'm firing again today and hope to get a little extra glazing done today so that I can fire a kiln once more this week.

purple underglaze painted on top of fired orange background underglaze (don't worry, it will be wiped away, next)
Yesterday I had trouble getting warm in my studio so I kept taking hot tea breaks to try to warm up and therefore didn't get much accomplished. I finished up most of my under glazing, but not all of it. I have three pieces left to finish, as well as some colored glaze I plan to spray later today.

work waiting to be underglazes and glazed

This morning, though it was a little wet and fairly chilly, I set up my little spray booth outside and sprayed most of the small pieces with a clear glaze. The clear glaze is annoying to apply, since the pieces tend to roll around if you hit them to hard. The glazed pieces are also annoying to load in the kiln since they each need to be set on stilts. The pieces are glazed on all sides, but if I set the glazed side directly on the shelf, the silica in the glaze would melt, sticking the whole piece to the shelf. With a stilt, the piece is held up by a small metal point and the fired glaze just pops off.

glazed work waiting to be loaded in the kiln

I also reapplied glaze to a few mugs that I had fired a while back. The first, fired coat of glaze wasn't thick enough so I added more and am refiring them to melt the glaze better.

reglazed mugs and a sculpture base in the kiln

The kiln is firing today and should be out tomorrow. My to-do list, as always, is long, and I vaguely hope that I might fire twice, glaze more work, clean the studio and put together fired work and bike parts before Christmas. I probably won't get all of this done, since I also have a bit of work to do for school.
my kiln, firing

Saturday, December 13, 2014

Santa's Workshop

Today was Santa's Workshop at Larson Gallery. It was so amazingly crowded and busy. Last year was the first year for the event and we had a decent turnout, but it never got really crowded.  The goal of the event is to encourage more kids and families to come to the gallery and feel welcome. This year it really worked. For a significant amount of time, I could barely walk through the gallery because there were so many people waiting to see Santa.

Last year I championed the creation of the event as a kid-friendly time in the gallery. Though I finished my term on the Larson Gallery Guild board earlier this year, I continued to help organize the second year of the event. This year our advertising (on Facebook and elsewhere) really paid off because the place was at least four times as crowded as last year. Kids came to see Santa, decorate cookies and create a tissue paper tree. They could also write a letter to Santa, who promised to read them all. Quite a few parents enjoyed making their own tissue paper trees and most of the most patiently and ornately decorated trees were done by artists over age 12. 

unfinished tissue paper trees

I did a fairly terrible job of taking pictures at the event, though you can see pictures on Larson Gallery's Instagram and maybe eventually on their blog. I spent most of my time refilling glue cups and making sure the kids had paper tree bases and enough tissue paper squares. I also did some Christmas shopping, since the small group of artists represented some excellent ceramic pieces, beautiful jewelry and fascinating prints. I also had some work for sale. I believe I sold three little sculptures and I saw three different little boys hanging onto their pieces during the event. I've got a good audience (admittedly one with limited purchasing power).

some small sculptures similar to those the boys bought
We had some excellent help from Larson Gallery members and staff and from some YVCC student ambassadors. The event was supposed to last 2 hours, but the place was busy for at least another half hour besides. The student ambassadors worked hard, with some Larson Gallery Guild members, to cut tree templates and tissue paper squares and instruct kids and parents on how to do the project. There wasn't quite enough room for everyone to sit throughout the event, so by the end I noticed that the approach to the project had been changed for some of the people. We started by telling people to wrap a tissue paper square around the end of a pencil and dip it in glue. Later I saw kids spreading glue onto their trees with the end of the pencil itself or dipping the wadded tissue paper into the glue with their fingers. Needless to say there were some sticky hands and pencils by the end.

Sunday, December 7, 2014

Raku Firing & Kiln Trouble

This was a busy firing week at school. We fired two and a half cone ten glaze firings in the gas kiln during the week and spent Saturday raku firing outside. We also fired several bisque and low temperature glaze firings in the electric kilns. Monday is the final critique for my beginning classes, so we are obviously getting as much work finished as possible.

Our school raku kiln shortly after we started firing on Saturday.

Now normally we don't fire half a glaze firing, but this was my first experience with a thermocouple that failed during the firing and caused the kiln to automatically shut off. The kiln went from 1949 degrees Fahrenheit at 4:20pm to 2400 degrees at 4:40 and the kiln shut itself off. I wasn't worried that it had actually gone up 450 degrees in twenty minutes, since the kiln has fired in a predictable way for dozens of firings and the pyrometric cones in the kiln weren't even soft. However, when I tried to restart it, the kiln kept automatically shutting off and I eventually gave up and let the kiln cool down.

Loading the barrel smoke firing.

Later I learned that the thermocouple is designed to read the highest possible temperature when it breaks, thus triggering the automatic shutoff. I also learned how to bypass the broken thermocouple for future firings. That night, however, I didn't feel comfortable taking the wiring apart during the firing. We let the kiln cool, added a few more cone packs to help us gauge temperature and refired on Saturday.

An independent student instructing a beginning student on how to load the barrel.

The raku firing this weekend went fairly well as far as weather and the pieces were concerned. We finished a bit early with all the pieces fired and my students helped clean up the leaves and paper in the kiln yard. The day was sunny and relatively warm by the early afternoon.

Adding shredded paper to the barrel before lighting it.

Our first propane tank froze up after the third firing.

Red/orange heat in the raku kiln top during firing.

After the firing I encouraged the students to move some of the detritus of the studio, including extra shelves, bricks and kiln posts to a different part of the kiln yard.

Pulling work from the reduction bucket after raku firing.

I think the students who fired were generally pleased with their work. The day included more students studying than most raku firings. We had intended to fire in November, but the weather prevented the firing. This firing was about as last-minute as it could have been as classes ended Friday and finals begin Monday.

A raku glazed piece cooling after post-firing reduction.