Working with clay is a bit like working with food, especially pastry, so let’s continue the cooking analogy and put the completely air-dried work (it might take several days) in the oven because that’s all the kiln is - an oven. It has switches and gets hot. In our case a bit hotter than your kitchen oven - about 1840 degrees F (1005 degrees C) or Cone 06 as kiln heat is meas- ured. Most kilns will have a little device called a kiln- sitter on the side of the kiln into which a litle clay cone fits and this becomes a shut-off switch when the kiln reaches the right temperature. More recent kilns may have an electronic controller, which is a lot easier to use than the timer on your oven! The clay suppli- ers will give you information on what you need for your particular kiln. Tn your oven you have racks. In a kiln you have shelves, which you separate with three props, keeping these vertically lined up with successive stacks. (See fig. 1) = | U Stacking kiln shelves Fig. 1 For the first firing (bisque) it does not matter if things touch. In a glaze firing, pieces not only must not touch but also there should be no glaze on the bot- toms of pieces and additional protection can be given by coating the kiln shelves with kiln wash. (A bit like putting a tray under a casserole that might bubble over!) The usual plan for firing is to give it three hours on ‘low, three hours on ‘medium? and on ‘higt? for as long as it takes. For most smaller kilns this should not take more than five hours. Check in with your sup- plier and monitor your Ist firing so you have an idea how long things take. A kiln sitter has a built-in timer, so note how long it is on high. After this first firing, dont set the timer too far beyond the time you expect it to take as the timer is an extra safety switch to avoid possible over-firing. Glazes are glassy protective and/or decorative finishes. The glass comes from silica, which is a major part of clay. To stop the glass from running all over the place, alumina is used. This is the other main part of clay. So we have clay on clay. In order to melt the top coat- ing it also has. a Flux (flux is Latin for melt.) If we 10 Clay for Dummies - Part Two want colour, this can also be added in the form of a metal oxide. (Eg. Copper Oxide would give you turquoise). What you have is a recipe - just like cooking! Just like bought, prepared food, commercial glazes, especially if purchased in small pots, can be prohibi- tively expensive. You pay heavily for convenience. An excellent compromise is to buy ready prepared dry glaze and mix it with water as needed with a little hand mixer to a ‘heavy crean’ consistency. The glaze comes in clear and white. You can mix the two for a milky glaze. Asa price comparison, if you bought a gallon of glaze in four ounce pots it would cost $122.00. For slightly less you can buy a fifty pound sack of dry glaze - enough to make up two thirds of a garbage can of glaze. If several people get together you can get enough basic clear and white glazes relatively cheaply in quantities to last for years. The easiest way to use this is to coat the pieces with the glaze by brushing on a couple of coats. Remember that it is the solids that make the glaze, not the water! Then you simply paint the colours on top using oxides and glaze stains. Here is the recipe - keep it stirred in use. I keep it in litle yoghurt pots. 1 cup water 1 teaspoon dry clear glaze powder 1 teaspoon glaze stain (or more depending on how strong you want the colour) This decorating technique is called Majolica and is the basis of Mediterranean and Mexican pottery. You can also just use oxides as stains on their own by mixing with water, brushing on and then wiping off with a clean, damp sponge. This will emphasise form and texture, as hollows will be left darker. I's a good way of dealing with sculpture. The oxides become permanent finishes but do not melt so you can do them all over. If you want to oxide some areas and glaze others, always oxide first. The cheap oxides for this are: Red Iron Oxide (rust) for reddish browns Copper Carbonate for black. Don't be fooled by the green colour, in firing it changes to cop- per oxide which is black. Manganese Dioxide on its own is also black but it is very strong. A mixture of it with Iron oxide is one I use a lot. You can use glaze stains like this too, especially on white clay and you can be quite painterly but the very aesthetically uncomfortable for me about paint- ing functional pieces. But that’s another article... India Ink and black shoe polish is a great, simple and effective sculptural finish and you can do remarkable things with pencil crayons. You might want to try Pic Firing, which will give you random flashings and carbon colouration. (See fig. 2) T used this with students at Burnaby North on a huge group mural and J do a great little project called ‘Little Figures of the Earth’ in which the students imagine themselves as archaeologists finding ritual fig- urines from some ancient, long-lost culture (which they invent). After bisquing, the figures are pit-fired and later discovered in the ashes. Finally, lets look at organizing the kitchen. You can use cardboard for work boards and desk cov- ers. You can get large sheets free from appliance stores. Recycled, thick-walled card tubes make adequate, free rollers. For the Cadillac version you can get dowel rod from Rona. Strips of wood for rolling guides (about 5/16 is about the right thickness for most things you will do) can be cut easily from the edge of scrap two by four by your friendly wood-shop teacher. I tell my SFU students that one of their best investments is a six-pack for this teacher! Dont waste money on tools, get old kitchen knives and some forks from Value Village and dont forget to pick up one of those little hand mixers while you are there. clay-cutting wires can be made from fishing line and a couple of washers. Modelling tools can be made from cheap chopsticks - a pointed and a chisel end will cover most needs. A discarded foam cushion will give you free sponges and old credit cards make great scrapers! You will need a couple of ice-cream buckets for recy- ding dried clay and a little plaster batt for reconstitut- ing the slaked clay. This can be cast from plaster of Pais ina lightly oiled baking tray. Sprinkle the plaster into water in a plastic bucket (estimate about three quarters the volume that you will need) until it peaks out and will not absorb any more. Let it sit for 3 minutes then stir and tease out any lumps. Pour into the mould. When the plaster has set, remove it from the mould and let it dry (several days.) Clay that gets too dried out can be slaked down with water in the ice-cream pails and then tipped out onto the plaster batt. The plaster will suck out the excess water and the clay can be wedged up and re-used. The trick is not to get a lot of clay to recycle. Do an ice cream pail as soon it’s full and you are starting the next one. stains are much more expensive. Keith Rice:Jones There are non-ceramic ways to finish clay but please, lets keep these to sculptural work. There is something Suppliers: Greenbamn Potters Supply Ltd ‘The Mad Potter Vancouver Island Potters Supply 9548 192nd Street #6 3071 No.5 Road #5 - 2071 South Wellington Road Surrey, BC V4N 3R9 Richmond, BC Nanaimo, BC 604 888 3411 604 244 3734 205 716 9960 Potters Guild of British Columbia Newsletter November/December 2005