Short for 'terra sigillata' the Romans used it to cover their pots. It's a clay slip made of only the finest clay particles. Brushed on in several thin coats, it almost shines itself. It's very cool stuff!
For my first attempt, I just used some old dried out white stoneware clay scrap I had. Searching around on the internet and the clayart archives, I'd found several recipes, the most definitive being Vince Pitelka's procedure. Not having all the equipment and chemicals needed, and just wanting to do a rough first draft, I found this article on Ceramic Arts Daily by Joan Carcia.
(Ceramic Arts Daily is a nice site, and free to join)
Being a rough test, I found I had about 2lbs of dried clay, so I used about a gallon of water, and a tablespoon ful of TSP that I found at the local building/home store.
After settling and siphoning, I poured it into a biqued bowl I hadn't gotten around to glazing yet to evaporate/absorb some of the water off. (Tip: soak the bisqe in some water first to get the pores of the clay 'siphoning' quicker)
I'm finding the white sig is working very well. Outstanding actually, for the sloppy way I followed the directions. I now have a larger batch made with red clay scraps settling, and will need evaporating. I just tried using some I siponed of the top yesterday and it's just too thin. I rubs right off when I try and polish it.
This time around, I was looking for the quick and dirty way, since I wanted to try it on some pots headed to a saggar firing in a couple weeks and I had to get them bisqued. My next attempts will be following Vince's process, and I can't wait to have some super sig to experiment with!
Saturday, July 26, 2008
Sunday, July 20, 2008
Saggar firing
Saggar firing is the most recent technique I've tried. The term comes from clay containers that the ancient Asian potters would put their pots in to protect them from the wood ash in the giant wood fired kilns they used.
While clay saggars are still used, their purpose is now often transposed. Many potters now use them to trap ash, smoke and other fumes with the pot inside, in order to concentrate the effect on the surface.
The particular method we used was actually wrapping the pots in aluminum foil, after placing sawdust, bits of steel wool and copper pot scrubbie and more inside. After tightly closing the foil, they're tumble stacked in the kiln and fired.
After firing and cooling the pots are unwrapped, washed and scrubbed clean. Again, if the original ware was burnished, they can be waxed and polished.
For more posts about saggar firing, click on the SAGGAR tag below.
While clay saggars are still used, their purpose is now often transposed. Many potters now use them to trap ash, smoke and other fumes with the pot inside, in order to concentrate the effect on the surface.
The particular method we used was actually wrapping the pots in aluminum foil, after placing sawdust, bits of steel wool and copper pot scrubbie and more inside. After tightly closing the foil, they're tumble stacked in the kiln and fired.
After firing and cooling the pots are unwrapped, washed and scrubbed clean. Again, if the original ware was burnished, they can be waxed and polished.
For more posts about saggar firing, click on the SAGGAR tag below.
Naked Raku 102
After the bisque firing, we prepared for the final firing. All of this work took place on the final class.
We coated our pots with a special crackle slip that's made to shrink. This makes it crack up and peel a bit during the firing and smoking process, like a mud puddle in the summertime. It won't actually melt and bond to the pot in the firing, and it will be scraped off afterward. Any larger areas we wanted to be black were left bare. Some people left the rims and collars exposed, or a design on the pot itself.
Then a thin 'glaze' is brushed onto the slip coating. It's job is to try and hold the slip together through the firing. You don't want to get it on any exposed areas of the pot, since it will bond to the clay and makes an ugly blistery mess. Unless that's the look you're going for.
The pots are fired to temperature, which is done more by feel than anything, observing how the surface looks and how the glaze is melting. They are then pulled out and placed in a metal can with sawdust or similar in the bottom. This instantly ignites, and after the flames are going good, an airtight lid is clamped in place. This makes the fire smoke, and this smoke penetrates the clay where the cracks in the slip coating are. After the pot cools, the lid is carefully opened since once air is allowed back in a flare up is very possible if the pot is still hot enough. The still hot pot is sprayed with water which helps crack off the slip/glaze coating now that it's job is done.
We finished by scraping off the slip/glaze coat with metal ribs. After they had dried off the burnished pots could be waxed and buffed with a hard paste wax.
We coated our pots with a special crackle slip that's made to shrink. This makes it crack up and peel a bit during the firing and smoking process, like a mud puddle in the summertime. It won't actually melt and bond to the pot in the firing, and it will be scraped off afterward. Any larger areas we wanted to be black were left bare. Some people left the rims and collars exposed, or a design on the pot itself.
Then a thin 'glaze' is brushed onto the slip coating. It's job is to try and hold the slip together through the firing. You don't want to get it on any exposed areas of the pot, since it will bond to the clay and makes an ugly blistery mess. Unless that's the look you're going for.
The pots are fired to temperature, which is done more by feel than anything, observing how the surface looks and how the glaze is melting. They are then pulled out and placed in a metal can with sawdust or similar in the bottom. This instantly ignites, and after the flames are going good, an airtight lid is clamped in place. This makes the fire smoke, and this smoke penetrates the clay where the cracks in the slip coating are. After the pot cools, the lid is carefully opened since once air is allowed back in a flare up is very possible if the pot is still hot enough. The still hot pot is sprayed with water which helps crack off the slip/glaze coating now that it's job is done.
We finished by scraping off the slip/glaze coat with metal ribs. After they had dried off the burnished pots could be waxed and buffed with a hard paste wax.
Saturday, July 19, 2008
Naked Raku 101
Naked raku gets it's name from the fact it's fired fast in a small kiln, and naked because it's not glazed. I took a class a few years ago and had a blast. Depending on all the variables, you get white pots with various black crackle patterns. Everything from large branches looking like lightning, to thousands of tiny ones.
The recommended clay body was just a standard raku clay that many clay suppliers make. It has a larger amount of grog and/or sand to help it take the thermal shock it's going to get later. Grog is coarsely ground, fired, fireclay. With the sand, it's the 'grit' you feel when you're throwing on the wheel. It s VERY rough on your hands!
The other clay a few people used was a high talc earthenware called Miller 10T. The talc also helps with the thermal shock. Since it didn't have any grog, they were actually able to burnish their pots to a smooth shiny surface. For my first raku attempt, I opted for the raku clay. I didn't want to end up with a pile of shards for my efforts!
As far as throwing, you want to make sure your walls are not too thick, and they need to be uniform thickness. A very thick wall will expand and contract at a different rate on the inside and outside, cracking. The same goes for any thin or thick spots. If you have a thin section going around your pot, it very well could crack around the ring, decapitating your pot.
When the pots were leather hard, the talc people trimmed and burnished theirs, the raku people just trimmed. After they were bone dry, they were bisque fired in an electric kiln to cone 05-06.
Continued at Naked Raku 102 . . .
The recommended clay body was just a standard raku clay that many clay suppliers make. It has a larger amount of grog and/or sand to help it take the thermal shock it's going to get later. Grog is coarsely ground, fired, fireclay. With the sand, it's the 'grit' you feel when you're throwing on the wheel. It s VERY rough on your hands!
The other clay a few people used was a high talc earthenware called Miller 10T. The talc also helps with the thermal shock. Since it didn't have any grog, they were actually able to burnish their pots to a smooth shiny surface. For my first raku attempt, I opted for the raku clay. I didn't want to end up with a pile of shards for my efforts!
As far as throwing, you want to make sure your walls are not too thick, and they need to be uniform thickness. A very thick wall will expand and contract at a different rate on the inside and outside, cracking. The same goes for any thin or thick spots. If you have a thin section going around your pot, it very well could crack around the ring, decapitating your pot.
When the pots were leather hard, the talc people trimmed and burnished theirs, the raku people just trimmed. After they were bone dry, they were bisque fired in an electric kiln to cone 05-06.
Continued at Naked Raku 102 . . .
Wednesday, July 16, 2008
Alternatives (pt. 2)
So what else is there, if glazing isn't your thing?
LOTS.
You might want to explore Naked Clay
by Jane Perryman.
I found it almost liberating once I took glazing off the table. It was as if the whole time I was wedging the clay, throwing the piece, shaping, trimming, drying, I was worrying 'How am I going to glaze this??'
My first expedition into the unknown was Naked Raku. It was a 7 week class taught at the art center that gave a great overview of the process as well as advice and guidance in what types of forms may or may not (there are few absolutes) work well. Most of us used an actual raku clay body, meant to withstand the shock of being pulled out of a 1700-1800F kiln into the air with tongs, and sometimes even plunged into water to cool! We weren't quite as hard on our pieces, but it's still amazing what clay can survive. The raku clay gave the pieces a somewhat rough texture.
Then I took a class on burnishing and saggar firing. I really loved it. We used regular white stoneware and burnished the leather hard pots with a stone. After firing, they were scrubbed clean and waxed with a hard floor wax. The burnished surface is silky smooth, yet still very natural.
Lately, I've been playing with using terra sigillata for an even smoother surface with less fuss than burnishing. I'm really liking the results. I can't wait to see how these pots take the color of the saggar firing in a couple weeks.
LOTS.
You might want to explore Naked Clay
by Jane Perryman.I found it almost liberating once I took glazing off the table. It was as if the whole time I was wedging the clay, throwing the piece, shaping, trimming, drying, I was worrying 'How am I going to glaze this??'
My first expedition into the unknown was Naked Raku. It was a 7 week class taught at the art center that gave a great overview of the process as well as advice and guidance in what types of forms may or may not (there are few absolutes) work well. Most of us used an actual raku clay body, meant to withstand the shock of being pulled out of a 1700-1800F kiln into the air with tongs, and sometimes even plunged into water to cool! We weren't quite as hard on our pieces, but it's still amazing what clay can survive. The raku clay gave the pieces a somewhat rough texture.
Then I took a class on burnishing and saggar firing. I really loved it. We used regular white stoneware and burnished the leather hard pots with a stone. After firing, they were scrubbed clean and waxed with a hard floor wax. The burnished surface is silky smooth, yet still very natural.
Lately, I've been playing with using terra sigillata for an even smoother surface with less fuss than burnishing. I'm really liking the results. I can't wait to see how these pots take the color of the saggar firing in a couple weeks.
Sunday, July 13, 2008
Alternatives (pt. 1)
Currently, I've been focusing my work on what I'd call alternative surfaces and firings. This is not your standard high-fired, glazed stoneware dinner service. While I still do a few functional glazed pieces, mainly bowls and vases, most of what I've been making will end up low fired, unglazed, porous, and not food safe. Not to say it's entirely non-functional, since you can always slip a vase liner or glass votive holder inside for flowers or a candle.
Honestly, I've just never been fully comfortable with glazing. That may very well change some day when I have control over my own glaze kiln and glazes. But as things stand now, I find it difficult to get the more consistent results one would expect from glazed ware. Even then, I tend to prefer the more 'predictably unpredictable' glazes like crystalline, ash effects, and layered crawl glazes. Again, things you can't really experiment with in a community kiln, and with good reason!
My first teacher also gave me an appreciation of the bare clay surface. As you work with clay and see it through the stages of becoming a finished pot, you gain a sense of the texture of the material. For me, after a while, covering the natural surface with a uniform, hard, smooth layer of glass started to feel wrong.
Continued . . .
Honestly, I've just never been fully comfortable with glazing. That may very well change some day when I have control over my own glaze kiln and glazes. But as things stand now, I find it difficult to get the more consistent results one would expect from glazed ware. Even then, I tend to prefer the more 'predictably unpredictable' glazes like crystalline, ash effects, and layered crawl glazes. Again, things you can't really experiment with in a community kiln, and with good reason!
My first teacher also gave me an appreciation of the bare clay surface. As you work with clay and see it through the stages of becoming a finished pot, you gain a sense of the texture of the material. For me, after a while, covering the natural surface with a uniform, hard, smooth layer of glass started to feel wrong.
Continued . . .
Saturday, July 12, 2008
Beginnings
So how did I get started in all this?
When I was a kid, my mom took some ceramics classes at the local college and it just always looked like fun. The idea that you could make something out of mud and bake it and turn it into ceramic was just cool! I was too young to take a class, but she found a lady across the street from my piano teacher that made slipcast pieces you could paint and glaze and she would fire. I must have made a hundred various things.
Fast forward 25 years. I've been transplanted to North Carolina. My wife and I are visiting the NC Zoo in Asheboro, and exploring our new state, when we discover Seagrove, NC and the North Carolina Pottery Center. After looking at the exhibits in the main building, we went out to the education building where Linda Russell was giving a demo. We were the only ones there, and after about the 10th question I asked, she cleaned off her wheel, got up and said 'Sit down. The only way to know it is to do it.' I still have that small, squat pot I threw that day. I was hooked.
Months later, I discovered Raleigh Parks department's Art program, and that I'd been driving past the Pullen Arts Center twice a day on my commute. I've been taking classes and using the studios ever since.
When I was a kid, my mom took some ceramics classes at the local college and it just always looked like fun. The idea that you could make something out of mud and bake it and turn it into ceramic was just cool! I was too young to take a class, but she found a lady across the street from my piano teacher that made slipcast pieces you could paint and glaze and she would fire. I must have made a hundred various things.
Fast forward 25 years. I've been transplanted to North Carolina. My wife and I are visiting the NC Zoo in Asheboro, and exploring our new state, when we discover Seagrove, NC and the North Carolina Pottery Center. After looking at the exhibits in the main building, we went out to the education building where Linda Russell was giving a demo. We were the only ones there, and after about the 10th question I asked, she cleaned off her wheel, got up and said 'Sit down. The only way to know it is to do it.' I still have that small, squat pot I threw that day. I was hooked.
Months later, I discovered Raleigh Parks department's Art program, and that I'd been driving past the Pullen Arts Center twice a day on my commute. I've been taking classes and using the studios ever since.
Sunday, July 6, 2008
Who is this guy ??
Short answer:
a guy who got bit by the pottery bug years ago and just can't stop being fascinated by the endless techniques, textures, forms and colors that are possible in clay.
Longer answer:
As long as I can remember, I've been attracted to clay. From the soft, slick blue-grey clay on the shoreline of a Michigan lake, to running straight into a bright red Georgia 'mud puddle' (I was probably about 4) and getting stuck! My dad had to pull me right out of my shoes to get me out of that one. (thanks, Dad!)
And the fires.... cook-out fires, charcoal grills, brush piles... I just loved watching (and playing with) the flames.
Now that I've 'grown up', my expression of choice is wheel-thrown vessels. I've tried hand-building on several occasions, but it never seemed to click for me. Most of the hand-builders I know say the opposite, so to each his own!
I work in stoneware, mainly because that's what the pottery center has available, but I also like it for it's versatility. I like being able to low fire it, or do a more traditional glaze firing.
I'm experimenting with different low-fire processes, raku, saggar, horsehair, and naked raku. (no, it's NOT what you're thinking.... the -clay- is naked, the CLAY...) Don't worry, I'll have more stuff up here soon to show what these all look like. But mainly, I'm having fun exploring the texture of the unglazed clay surface.
For more on how I got started, look here.
a guy who got bit by the pottery bug years ago and just can't stop being fascinated by the endless techniques, textures, forms and colors that are possible in clay.
Longer answer:
As long as I can remember, I've been attracted to clay. From the soft, slick blue-grey clay on the shoreline of a Michigan lake, to running straight into a bright red Georgia 'mud puddle' (I was probably about 4) and getting stuck! My dad had to pull me right out of my shoes to get me out of that one. (thanks, Dad!)
And the fires.... cook-out fires, charcoal grills, brush piles... I just loved watching (and playing with) the flames.
Now that I've 'grown up', my expression of choice is wheel-thrown vessels. I've tried hand-building on several occasions, but it never seemed to click for me. Most of the hand-builders I know say the opposite, so to each his own!
I work in stoneware, mainly because that's what the pottery center has available, but I also like it for it's versatility. I like being able to low fire it, or do a more traditional glaze firing.
I'm experimenting with different low-fire processes, raku, saggar, horsehair, and naked raku. (no, it's NOT what you're thinking.... the -clay- is naked, the CLAY...) Don't worry, I'll have more stuff up here soon to show what these all look like. But mainly, I'm having fun exploring the texture of the unglazed clay surface.
For more on how I got started, look here.
Subscribe to:
Posts (Atom)
Posts
