The materials that modern potters use to compound glazes (or which are compounded for them)
are not made for potters. This market is too small to be of interest to the Great Satan Club. These materials are
made by industry for the machinery of industry. Machines cannot deal well with variability. Their "stuff" must
be refined. In other words the character must be removed. Using this "stuff" it is easy to make drab or garish glazes.
Anything else ... maybe not. Good results are easier with local, unrefined, rocks, clays, volcanic ashes, scrap metal, sands,
whatever; as long as you know where it is from. As long as you know where you are from. The only essential machine
is a ball mill. (See Pioneer Pottery by M. Cardew).
How to make a Glaze
- Granite ... 80
- Limestone ... 10
- Clay ... 10
To prepare granite or pegmatite or many other rocks for use in glazes:
- Fire to red heat
- Pulverize(to a coarse sand). A hammer will do this although a hammer mill is easier.
- Mix in proper proportions in a ball mill with the other materials in the glaze receipe and
mill until all the material in a six ounce cup can be washed through a 200 mesh screen leaving no
more than a eighth of a teaspoon of residue.
- Read Cardew, Davies and Leach.
- Phone me if you have questions.
Present receipe for Moose Mountain White Stoneware glaze
Mill 12 hours. Use as thick as possible.
Fire to cone 10 with 10% carbon dioxide reduction.
Add St. Victor volcanic ash for the best celadon I have ever seen. Calcine most of this ash.
I like pegmatite, a kind of coarse grained granite. It is available locally as 'erratic' glacial boulders. A good place to see
pegmatite is at km. 250 of the Hanson Lake Road. There the road is in the Shield and cuts through vertical walls of rock 10
feet high. The pink rock is potash feldspar (moonstone). It's nice. The white stuff is quartz and the black flaky rock is biotite mica.
Near Mafeking, Manitoba there are limestone deposits with ancient fossilized sea shells clearly visible. Crushed oyster
shell that is usually used as chicken feed also works as a substitute for limestone. It's what I use.