This talk, by Andrew Carran, is the beginning of a project for members to gather soils from around Christchurch / Canterbury to make glazes. Andrew is a retired geologist who has worked in many countries around the world and he likes to make glazes from soils that he finds around Chc. Halswell and Lyttelton, to name a couple, were on display.
The project goes from here; members, who have signed up, will spend the next two weeks looking for appropriate soils. Much of the soil around Chc and up on Banks Peninsula is Loesse; this soil is approximately 50% silica, 25% aluminium and the remaining 25% is various oxides, carbonates and trace minerals. Mud flats, of a sticky, muddy nature, are also a good potential source of 'interesting' soil. Any soils gathered will be dried and where possible ground down to small particles ready to be made into a glaze.
First we started with a very busy clubnight which was very informative with lots of glaze samples, soil maps of the greater Christchurch region and lots and lots of information, so much to take in.
Six of us and Andrew got together to work on our own glaze projects. We had soils, sands, loess and clays from the harbours to Gore Bay and all the way to the Craigieburn Ranges. We started with preparing our particular base material by breaking it up and siveing it into very fine particles.
Lunch was a wee outing to a lookout overlooking the Canterbury plains. Andrew shared stories about the old brick works in town, where the raw materials came from and clay works in a number of different locations in the distant foothills of the Southern Alps; a highlight of day one.
Then it got pretty messy, with measuring, mixing, adjusting our glazes and glazing many test tiles. We are now in the process of firing our glazes to Cone 5/6, Cone 7/8 and Cone 9 before we potentially adjust them some more to desired outcomes. Can't wait to see all out test tiles. Photographs of the work, so far, are attached. We'll have the test tiles and other work some time in the near future.
What a day, What a fire, What a result!
Only three of us went out to Rangiora which was a shame; we were welcomed by a good number of their folk. Stacking of the kiln began when Les Freeman, Chief Salt Kiln Operator, arrived with some fire wood. There is a special technique when stacking this type of kiln because the gas flow is to be made turbulent. Different shapes of pot are placed near each other to accentuate the variation in the gas flow. The were too many pots for everyone to get all their pots fired, so we made sure that everyone got at least one fired. Lots of pots with no names, so hope you didn't miss out.
The firing is started using wood; this is to heat the fire box to the point where the diesel / air mixture will ignite. The kiln was set alight at 10.00am on a beautiful Nor'wester day; lots of smoke to begin with as the heat-up continued. The roar of the diesel/air mixture is a bit like a Boeing 747, but the sound of the roar varies during the firing and all fire adjustments are made based on the changes to the roar.
The kiln is a double skin, dry stack type and as it heated the flue obtained a slight lean; nothing to be concerned about apparently. The nature of the build enables keen viewers, like us, the opportunity to see the kiln heat through dull red, bright red, brighter red with a touch of yellow and then with a touch of white; absolutely fantastic. Then, we got to throw the salt in. A cup of salt is wrapped in newspaper, the is dampened with a quick dunk in a bucket of water, then the projectile is thrown into the fire box with the aim of reaching a far back as possible. There were a few "drop-shorts" but generally all the salt got into the kiln and did its thing. The clouds of white/grey smoke are the result of the salt under combustion. The firing stopped and the kiln was closed up around 4.30pm. The Nor'wester was given as the reason for the shortest firing they've ever had.
The photographs below show some of the excitement of the firing and also some of the results. The price for getting a pot fired is $10.00 (that's the RPC standard fee), so Ill be around collecting over the next week - ten days.
There is talk of another salt glaze firing in six to eight weeks time; I highly recommend it. Commit to the whole day and get involved; at the risk of repeating myself, its absolutely fantastic.
Regards - Graham, Jon & Robin
The Secretary and Members - Mt Pleasant Pottery Group.