Pottery Workshop News
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This page contains news of our activities in the pottery workshop. Information and pictures of what we do in order to produce our ceramics are displayed. In addition, we hope to explain some of the considerations required to make a successful ceramic item, that looks and feels good and, if functional, works well. Check back from time to time to see what's new, and scroll for latest news.
Firing at 1200°c part 1
Arthur has a gas kiln and electric kilns. For many years, he would fire in his gas kiln up to 1300°c with glazes he made himself from raw materials. He formulated a clay body with a blend of ball clay and molochite. This would become vitreous at this temperature, thus providing the properties necessary for stoneware pottery, which would be truly watertight and sturdy. This method of working served well for many years, firing bisque in electric kilns and glaze in a gas kiln.
However, two years ago, he was asked to start up a pottery class, whereby students would learn about pottery making, and this involved the management of large quantities of other people's pottery. It became apparent that it was not convenient or viable to gas fire so Arthur set about organising a range of new, convenient glazes which would appeal to his students. These would require firing at 1200°c, as opposed to 1300°c. He continued to use the clay body he made himself, which was perfectly fine for most purposes, but Arthur felt uneasy that the clay was not 100% vitreous at this temperature, which falls between earthenware and stoneware.
Arthur was surprised to encounter a difficulty in finding a manufacturer's clay with the right properties for glaze firing at 1200°c, so experimented with several samples of clays. This included a white earthenware with a recommended top temperature of 1160°c. Tests proved promising when he fired this clay to 1200°c. These tests involved small pots, and now Arthur is making a range of larger pieces to see how the clay performs at 1200°c.
To complement a clay body fired at 1200°c, Arthur has developed a transparent, white and 2 wood ash glazes to use with the range of favourites purchased for and by students. He has also discovered that a range of glazes from a prominent ceramics supplier, designed to flux between 1220°c and 1280°c, work just as well at 1200°c.
If the next firing of the experimental earthenware proves to be successful, all is poised to solve the initial problem of vitrification at 1200°C.
Arthur will post the results of the firing in due course, and meantime, he has displayed some pictures relevant to this project.
Tour of the workshop
Our studio workshop is divided into three rooms. We have a throwing room with three electric wheels and one momentum wheel. Housed in this room, also is the pug mill and two clay extruders. Two deep sinks with water also service this area and there is also a sturdy work bench. Extensive shelving is used for the storage of pots in progress and raw materials.
A second workshop provides space for hand-building, glazing and decorating. There is also shelving and most of the glaze buckets and materials are stored here. A work bench is situated around the wall.
The kiln room houses a gas kiln, a front loading electric kiln and a top loading kiln. This room is also used as a drying room. See the pictures of these workshops below.
Work in progress
The workshop is usually furnished with pots and ceramic items in their various stages of construction, by Arthur and his students. These provide striking images in the sunlight which steams into the throwing workshop in the afternoon.
Firing at 1200°c part 2
As reported in part 1, a white earthenware clay with a recommended top temperature of 1160°c was used to make a number of larger pots which Arthur has fired up to 1230°c, and in doing so he tested out the use of underglazes to paint some landscape scenes.
An initial firing up to 1200°c proved to be too low to satisfactorily flux the transparent cover glaze. The underglazes were painted onto bisque, with some resulting crawling over the white underglaze. The photos below illustrate these results.
Arthur will now try painting with the underglazes on raw pots, then biscuit fire, before applying a transparent glaze. It is hoped that this will prevent crawling. It is established that the white earthenware will vitrify at 1200°c, thus solving the original dilema, but Arthur may well, yet, retain the use of his own stoneware clay and fire up to 1260°c
Firing at 1200°c part 3
Having established that we have a clay which vitrifies at 1200°c, its use with underglazes on the raw pot proved successful, as no crawling took place after overglazing and firing. (Hitherto, this clay has been used in its smooth form, which is more difficult to throw for students. Therefore, Arthur is going to try the grogged version, which will open it up and improve its throwing properties.)
In addition, working with glazes which fluxed nicely at 1200°c provided excellent results and a sound product.
Samples are illustrated below.
Saying goodbye to the gas kiln - April 2019
After many years of service, we have decided to retire our gas kiln and invest in a new electric kiln with a programmable controller.
Dismantling the kiln involved using a cold steel chisel and an angle grinder.
Some images below.
New Kiln - May 2019
Our new kiln has a 9.5 cubic feet chamber and is fully automated with a computerised controller and auto dampers.
The kiln room has also had a face lift.
Some images below.
New Glazes - June 2019
The new glazes have been made using raw materials. These are Nephaline Syenite, Flint, Ball Clay, Talc, Zinc Oxide and Whiting. Glaze stains and oxides were added to provide colour to this base glaze.
The glazes were applied to demonstration pots, thrown for Arthur's students.
Some images below show the pots fresh from the kiln.