Rachel Dorn Ceramic Sculpture: under glazing

Showing posts with label under glazing. Show all posts

Monday, December 25, 2017

Making Gifts

odd ball dishes that I threw before coming up with the plan to include textures for underglaze inlay

Once the quarter ends, I always think I will have time to spend reading and chilling. Instead, I usually fill up all the available time with new projects, like recording 50 videos and making sculpture examples for class, or like building a set of stacking cats and throwing dishes for gifts.

plates in progress

This December my over-ambitious time suck was making plates and bowls for my brother. Possibly this idea started out as a birthday gift but I quickly passed the time that would be appropriate for birthday. I have now passed the time that will actually get these to him by Christmas.

re-enactment of what my brother does with the dishes I made for him

My brother informs me that, like our family, they have been breaking the dishes I made them years ago. Apparently there's some sort of family competition for breaking pottery. My daughter is all-in on the competition, but she keeps breaking the pyrex bowls instead of the ceramic dishes. I'm ok with her approach, as more of our dishes are made by people besides myself and therefore harder to replace.

big plates with blue, purple and blue underglaze decoration

Anyway, I decided to replace some of my brother's dishes for Christmas. I took a day to throw, half a day to trim and then I figured the glazing would be pretty fast. I'm not sure why I thought this. Apparently because my time estimates are just way off when it comes to what I can make and how fast. This is a chronic problem that is most noticeable in December.

trimming plates = more fun than glazing plates

On Monday, a week before Christmas (because that's how I roll) I spent over 6 hours under-glazing the dishes. I know how long it took because I listened to almost an entire audiobook start to finish while glazing today and the Audible app tracked my work time.

three different size/shape of plates, notice that the set has only 3 of the smaller sizes because I already broke the others

I was trying to get the dishes glazed in order to fire them before traveling for the holidays. This is a bit silly, as I am unlikely to want to carry a bunch of dishes on the plane, and neither is my brother, but I did want to get the cats done in time for the trip and the plates and cats were going in the same kiln.

the bottoms don't match = fun!

I painted underglaze on the tops and bottoms of all the plates and the interiors and exteriors of all the bowls before bisque firing (because occasionally I do plan ahead). I then intended to apply a contrasting color to the indents and lower sections of all the plates and bowls followed by a coat of clear glaze.

the smallest plates

While I was throwing this seemed like a good idea. Several hours into underglazing the bisqueware I was convinced this was a terrible, horrible idea and the results would make me want to move to Australia.

the wacky not-matching dishes

When I unloaded the kiln, I was really happy with the results and stayed that way until halfway through taking pictures. I wanted to get pictures taken before leaving to see my brother so I could show him what he'd be getting (he doesn't need it all, so he can choose favorites).

I enjoy throwing bowls, bowls, bowls

I decided to go to the trouble of getting out my photo backdrop and table and stand and taking semi-careful pictures. I'm glad I did, though I drew the line at getting out my tripod and camera and just took cell phone pictures because I know for a fact that I should not be allowed to try to upload pictures on the same day as I plan to travel. I am already on technology time-out after an incident involving iTunes and a significant amount of foul language yesterday.

these bottoms don't match either

Joking and travel/holiday related anxiety aside, I actually am pretty happy with the results. Ironically, they look very different from what I planned. The colors faded and darkened in ways I didn't anticipate. My fears about how they would look around hour 4 of glazing were proven incorrect--to my relief.

the inside is only one underglaze for these little bowls---and my favorite

I am still not getting them to my brother by Christmas and I may even take some better pictures when I get home (yeah, that's not going to happen--Winter quarter starts January 2, so my brother will be lucky to get the dishes in January). I plan to grind down a few stilt marks, do a quality check, and then send on his favorites via UPS or something. Unlike the stacking cats (see this space later this week for an update on the nesting cats), these dishes I might actually make again.

my favorite to throw and to glaze

And now, with the dishes staying home, and me leaving the state, I should be able to avoid starting any ridiculous projects this week. Merry Christmas, everyone!

Sunday, September 17, 2017

Small Sculpture and Cracking Glaze

this sculpture with two others in 2015

I've been working on a couple pieces of sculpture since 2015. I built them in 2015, applied underglaze in 2016, but couldn't finish them until this year, maybe, because their surfaces are causing me an unusual amount of trouble.

the first layer of underglaze in 2016

The one that has caused me the most trouble is a simple vertical sculpture with three bulb shaped attachments. There's no problem with the structure itself, but I could not get underglaze to stay put. When I first applied underglaze, it seemed fine. I fired it in place, but when I went to apply a second coat of a contrasting color, the first coat started to crack off.

two layers of slip cracking off

I can't remember fired underglaze cracking off any other work I've done besides this sculpture and another made at the same time. Generally, if glaze or underglaze won't stick to a surface it is because there is wax, grease, or dust on the surface, but none of those substances should survive firing and scrubbing. I picked off the underglaze that was cracking and scrubbed the whole pot before reapplying another layer of underglaze, but after a second firing, that too cracked off in multiple places.

slip cracking off

At some point in 2016, I got mad and just covered the whole thing with throwing slip. I didn't expect this to solve the problem, but I was annoyed and didn't want to look at the piece anymore. The throwing slip cracked too, of course.

wet slip (you can see the circles of underglaze through the slip) and dry, cracking slip from 2016

This year, I decided to wash off the slip and see if there was anything to be done for the piece. Bits of hard, fired underglaze were still cracking off and where they cracked, they left a sharp edge and change in thickness that would show up through a new coat of underglaze.

grinding off the underglaze

I decided to use a wire wheel to grind off as much underglaze as I could. Grinding off the underglaze was satisfying but messy. Mostly the underglaze cracked off, sometimes it required grinding, and in one section, the red underglaze was adhered so well that grinding didn't budge it--at least the amount of grinding time I was willing to commit didn't budge it.

the red that wouldn't grind off

At the tight corners, the wire brush was too thick to reach the underglaze. As it wasn't cracking, I decided to leave it alone. The transition between the raised level of the underglaze and the raw ceramic was more gentle than where the underglaze cracked off, so I guessed the depth change wouldn't show through the next layer of underglaze.

the wire brushed sculpture

I kind of like the ground texture of the raw ceramic. The sand and grog has become visible as the smooth ceramics surface was ground away. The rougher texture makes the surface look like cement, but the overall result doesn't feel like something I had much control over. The hard-to-reach crevices show up purple and blue and the hard, irregular red section looks out of place.

the wire brushed surface

I decided to reapply a red underglaze over the body and purple over the already purple bulb/leaf shapes and just fire it with a gloss over the top of everything. The piece is now "finished." It doesnt' appear to be cracking, but neither is it all that exciting to look at. Though a lot simpler than many of my other pieces, its surface required much more effort than what shows up in the piece now.

the "finished" piece from 2015

As I was getting pictures ready for this post, I pulled the masking tape off of the other vertical sculpture from 2015 (seen in back right of the first picture in this post). I had masking tape in place to hold on a bike part I had epoxied in place to complete the piece. When I pulled off the masking tape, it pulled a cracked section of glaze and underglaze off the surface of the sculpture. Sigh.

glaze cracks show up (today!) in the other sculpture from 2015

Thursday, August 24, 2017

Under Glazing Three-Color Pods: Part 2

pods with their final layers of underglaze, before final glaze firing

Over the course of several weeks, I applied the bottom layers of underglaze for a set of six pod shapes. I fired three of the pods to cone 06 and three to cone 04, which is a bit hotter.

pod fired to cone 06 (left) and 04 (right)

The turquoise and red underglazes are darker in the cone 04 firing, because of the firing temperature.

yellow underglaze being applied to turquoise

Now that the first colors have been fired, they no longer wash away when wiped with a sponge. At this point I was able to add the contrasting colors over the top of the red, turquoise and purple.

yellow underglaze applied, drying

I began by painting bright yellow onto the turquoise textured background. I tried to avoid getting the yellow on the red, with varying levels of success based on how long I had been sitting in the studio and how bored I was of the process.

close up of yellow underglaze highlighting turquoise texture

Once the yellow was dry, I gently wiped away it away with a wet sponge. The yellow remained in many of the holes, but was washed away from the raised areas, revealing the turquoise color underneath. In this case, the yellow wiped away somewhat irregularly, both because the texture is irregular and because it is difficult to use even pressure with the sponge in the cramped areas between sprigs.

wiping yellow underglaze

The results vary now because of the temperature to which the six pods were fired, as well as because the slightly different shapes and spacings left the yellow more visible in some areas and on some pods than on others.

yellow layer complete

Next I applied dark blue onto the red sprigs, carefully avoiding the yellow and turquoise background.

blue underglaze applied

The process took a long time and to save my aching back and to make myself feel better, I moved to the couch for some of the blue application. There the cat kept me company.

applying blue underglaze with my helper

At one point, a friend stopped by. I kept applying blue while I talked with her. As she was about to leave, I took the now-blue pod into the other room and brought back a pod with red sprigs as yet uncovered. At first, she thought it was the same pod and the color had changed that quickly.

blue underglaze, wiped blue underglaze and raw red underglaze on three sections of one pod

Alas, I had to be the one to change the color. Once all the blue was dry, I grabbed a sponge and wiped away the blue in the same manner as the yellow, leaving the deep spaces of the sprig blue and the raised sections red.

close up view of wiped blue underglaze texture

I also added green to the purple interior/ends and wiped it away in the same fashion.

green and purple ends

The plan is to add a clear gloss glaze to all six pods and attach them to a rod once they have been fired. The group of pods will be raised up from a planter rather than laying on their sides as they are in my studio and in the kiln.

clearly the cat feels affection for my work

Sunday, August 13, 2017

Under Glazing Three-Color Pods: Part 1

pods with turquoise underglaze layer

One of the reasons I'm not a big fan of the process of under glazing my sculpture is that the process takes so long. I use layered underglazes and I realize that using underglazes, and using them this way causes my process to be slow and tedious. Unfortunately, I like the complex and colorful results.

purple underglaze layer

I have been trying to get a solid start on under glazing a set of six forms. There are three sections with different textures on each form and I want to highlight each section separately with two colors each for a total of 6 colors. The undercoats will be fired for stability, then the top contrasting colors can be added and wiped away. Commercial underglazes require at least three coats applied for even coverage, so that means a total of 9 coats (3 coats each of three colors) before firing. After firing, the subsequent coats will not need to be applied as thickly or as carefully.

under glazing at the table

During the first round I carefully applied three layers of turquoise on the base level of the whole sculpture, trying to avoid the sprigged sections. After I applied the turquoise three times and wiped away the excess from the sprigs, I applied three coats of purple to the end and three coats of red to each sprig. While I was applying the underglaze, I was careful to apply evenly for full coverage and no overlapping into other sections, but I also needed to be careful to not lose count of how many layers had been applied. Sometimes I could visually distinguish the first and second layer, but after that, all layers look the same.

edges of sprigs before clean-up

With so many sprigs placed in an irregular pattern, it is quite difficult to keep track of which sprigs have gotten a second or third coat of underglaze. What I generally do is draw a pencil line across each sprig (or several sprigs on each section) and apply underglaze until I cannot see any more pencil lines.

pencil lines and wet underglaze

Applying each coat of red took about 40 minutes per pod. I applied the turquoise in my studio but moved to the dining table for the red because the height difference between the chair and the table is more comfortable. On Friday afternoon and Saturday, I underglazed on the couch while watching marathon episodesof season two of The Great Pottery Throwdown.

the cat prefers me to glaze on the couch

Watching, or at least listening to the episodes helped ease the monotony of the process. Ironically, one of the contestants kept having trouble with time. I laughed at her struggles, but reflected that I had spent more time than her just completing the first part of the glazing on three pods. I also kept thinking of my friend Janice during the episodes, especially episode four with the fountains because she would enjoy both the show and trying some of the challenges.

third layer of red (looks a lot like the second)

I had been glazing almost all day long (with a few breaks for laundry, errands, and a game of Bananagrams played Scrabble-style) and I thought I could get all three completely finished before heading out to see The Warehouse Theatre's excellent production of Willy Wonka (it's really good; if you're in Yakima, I highly recommend it).

red and turquoise mostly complete

I was on track to finish before the show when disaster struck. I had just finished the third coat of red on all the sprigs of the last pod. I was going to go back and touch up the turquoise where it had worn off or had a drip or smear of red. I figured the touch up would take 5 or 10 minutes, then I could finish loading the kiln and program it to fire that night.

glazing with a lid as palette

I like to use the lid of the underglaze jar as a palette, especially when doing careful, detail work. I shake the closed jar to get some underglaze on the inside of the lid, then dip a small brush tip into the underglaze on the lid. Instead of dipping into the jar blind, the lid method allows me to get less glaze on the brush and keep the brush and the sculpture cleaner.

oops

I had just screwed the lid back on the red jar when I went to shake the turquoise. Of course, for some reason, I hadn't screwed the lid back on. When I shook the jar, the lid came off, the underglaze came out and splashed on the table, the pod, my shoe, the carpet, the brushes, my daughter's stickers, and pretty much the whole house.

oops ameliorated

By the time I finished wiping off the underglaze from all those surfaces, including the pod, it was time to leave for Willy Wonka so I didn't finish or load the kiln until the next morning. I'm not that bothered by the wiped look, and the plan is to layer more color on top, but I touched up the red with one more layer anyway. Maybe another day I'll try the splash technique and leave the result, but not today.

three fired pods (from earlier)

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