Extruded execution

So I decided to give my North Star 4″ extruder a workout this week, building two large 20lb. coil stoneware planters. I actually made the bases for the planters last week, using coils as well, then ‘threw’ each base on the wheel to smooth out what would eventually be the interior surface. I left the bases lightly covered in plastic on plaster bats for several days to get leather-hard.

The first leather-hard base was placed on the banding wheel, then scored and slipped, ready to receive the first coil. As each coil row was added, I used a wooden modeling tool to blend one row of coil with the next, then smoothed the outer sides with a small plastic rib.

The process was repeated until I had added several rows of coils and gradually widened the form to a final upper diameter of 17″. Since my extruder is installed right next to the work table, the process of cranking out coils, application, and building the form went quickly and efficiently.

Selecting just the right coil-sized die was essential for quick work, and keeping a bucket beneath the extruder made cleanup a lot easier.

Halfway through the building process I stopped building to allow the coils to set up, wedged more clay for the upper half of the form, and made some decorative tiles to later affix to the outside of the planter.

After the full height of the form was reached, I added one more coil row, this time using a slightly greater width coil to serve as the planet’s rim.


Lastly, I added some decorative surface patterns and attached the decorative tiles I had made earlier. The planter on the right below is shown further along in the drying process, and after the base was smoothed with a damp sponge.

When pottery moves in

Little corked jugs are curious forms. They nestle into any space and seem perfectly willing to take up permanent residence there. A case in point: some of these little guys have been on display for sale at SATO Salon Organics for a while and recently we figured out that they look so comfortable in their spot on the shelf that they avoid moving day. So, they’ll soon be placed in a new location at the salon, but my guess is that they’ll settle in comfortably once again.

The potter’s manicure

All my life my hands have been relegated to the unadorned among us. Oh the toenails saw some lacquer in the summertime, don’t get me wrong, but my hands always found themselves in too much water, sawdust, grout, or reduced by length and banned from polish due to someone’s rules and regulations.

From the dress code in high school to similar restrictions as a nurse in a Catholic hospital, my nail polish went underground,  inside my shoes. A later career change to teaching art kept my nails short and color-free as practicality won over vanity. I could count on less than two hands the number of professional manicures I’ve had. Once, when I returned home with a French manicure for a special occasion, the eye rolls from my daughters confirmed my suspicions that painted digits weren’t ‘me’.

Today during the day I still teach art, although it’s all digital – graphic and web design- but I’m a potter at night, on weekends, and holidays. Potter’s hands take a lot of abuse from having their hands in water, not to mention the sanding effect of the grout in the clay, and the incredible drying effect of stoneware on the skin. So, to keep my hands ready to wedge pounds of clay, plunge into buckets of water, and grind over grog-filled stoneware on the potter’s wheel, today I follow my own rules and regulations about short fingernail length and polish-free nails.

Pining for Porcelain

Lately I’ve been considering pottery work with porcelain. Mostly because the translucent characteristic of this clay body lends itself to all sorts of interesting outcomes. It’ll be trial and error for a while I’m sure, but therein lies the joy. Curiosity for how this medium will respond to various hand-building, printing, and wheel throwing techniques serves as the driving force.

The porcelain arrived quickly from the Ceramic Shop (Philadelphia, PA), so I tore open the box to check it out. From the outside of the bag the clay felt a little stiff, but from what I understand from YouTube videos, once the clay is well wedged, it softens up. I was careful to wash the surfaces, tools, sponges, buckets, and anything else that had previously come into contact with stoneware. Again, a YouTube video recommended washing tools, etc. so that no iron bits would contaminate the porcelain clay body.

I used a brand-new wire cutting tool and wedged the porcelain on a heavy piece of clean cardboard, since my bamboo wedging table’s surface was thoroughly embedded with stoneware from previous wedging. With only a pound or so, tried throwing a little vessel with a tiny spout. The clay handled nicely, was very easy to center and form – left the bottom a bit thicker for trimming a nice foot. Next, I threw a little one pound bowl and tried to make the walls as thin as I could without risking collapse. Again, I kept the base thicker so I could trim a deep foot.

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Pots that go pop

I should have known better. The bottom of that jug was heavy; I’d convinced myself I liked it that way and scaled back the amount I’d trimmed from the bottom. The problem was that I’d fired it along with the other ware that I had thrown on the same day. So, why I was surprised to see that shattered form in the kiln on Sunday morning was anyone’s guess.

Having taught high school ceramics for a few years, I’ve learned to read green ware (un-fired dry clay) for its readiness to be fired. Occasionally, student work blows up in the kiln, but it’s usually due to attachment mistakes – where air becomes trapped between two pieces of joined clay. Every once in a while a piece is fired that is not quite ready and that little bit of moisture remaining in the clay seals its doom. When firing hundreds of clay forms a week, a system is needed to determine which pieces are ready and which are not quite bone dry.

The surface of dry clay will feel dusty, but more than that it won’t feel cool, unless it’s been stored in a very cool room. Sometimes comparing the hand held temperature – as the form feels against the palm of your hand – of one form that you’re sure is completely dry with the questionably dry form, will reveal the difference. If I still can’t tell if a from is dry, I place that questionabe form against my cheek, a telltale cool sensation will reveal an ever so slightly damp form. I usually only use this technique when the hand held comparison method hasn’t helped me to decide on a given form’s readiness to be fired. This usually happens when I’ve unloaded a couple of kilns and my hands are very warm from handling all that warm pottery.

Working in an outdoor studio has its own set of challenges when drying pottery. Many humid days in a row can delay drying time significantly, and cool damp nights can have the same effect. Additionally, when the ware has taken on the ambient room temperature it can feel deceptively warm, as if it’s dry and ready to be fired.

I (finally) decided to create a system to address the extra drying time needed for that outlier form that is more dense than the rest of the lot. I’ve designated a section of a drying shelf for that one or two pieces of heavier ware to remind me to delay firing.

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Clay delivery

Delivery day is here.

That big white truck backed into the driveway and in a matter of minutes ten boxes of stoneware were stacked and ready for the next part of the journey. Thanks to my sturdy hand truck I had the clay stacked in the studio in about ten minutes. I’m no spring chicken, so I usually only transport two boxes (100 lbs. total) at a time. In five quick trips the clay was in place and that placement matters. Due to that once-a-summer deluge of rain, I stack the clay boxes onto an unfinished IKEA pine shelf-top; assuring that the boxes remain dry should a heavy rain seep across the floor.

One last step before the job is done is to clearly mark each box with the type of clay contained within. Perhaps if I were more fastidious, I’d place each box with its printed clay type  information clearly visible, but I’m usually just focusing on moving those 500 lbs. of clay.

Since clay shouldn’t be frozen, it can’t remain in the outdoor studio during the winter months, so I usually transport it inside and store it in the indoor studio from about late October through March. For now, it’s ready to use. Time to get to work.

 

 

Clay mix-up

It’s not the first time I’d ordered something that I didn’t intend to purchase, but this time it would have been 250lbs. of something I didn’t want or need.

The purpose of the call was routine, to schedule delivery of the 500 lbs. of clay I had ordered. The representative on the phone asked if I really intended to buy dry clay mix instead of wet clay. No! I replied and thanked her profusely for her interception; the time and energy she had just saved me with one simple question was golden. Customer service counts.

This experience should teach me to pay attention to the details, but there’s a lot of things I should do.

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Throwing properites of different clays

The #182 Standard white stoneware mentioned in the previous post is super easy to throw as it contains very little grog; it’s smooth and very pliable. The downside is that it might crack during drying if you’re not careful and allow the clay to dry too quickly or have uneven floor/wall thickness. The #112 Standard speckled brown clay is more rigid with lots of grog, a bit harder to throw compared with the white stoneware, but is nice and sturdy and rarely cracks. Glazes result with a speckled texture that enhances most glaze colors (image right).  The #259 Standard brown stoneware is smooth and easy to throw (image left), but I’ve had occasion where cracks form during bisque firing on larger/ wider pots; drying slowly helps to prevent this from happening. The downside to the rich brown finished clay color in oxidation firing (electric kiln) is that glaze colors are muted. However, experimenting with various glazes can result in some fun results (image center).

Waiting for clay

I’m down to a mere 75 lbs. of clay; 50 lbs. #182 white stoneware and 20 lbs of #112 speckled brown. Kelly is coming over to throw Wednesday, so I’m hoping the 500 lb. shipment arrives before then. If not, it’ll be tiny pots all around.