Lapidery suppliers stock silicone carbide grit. I use 600 mesh as I have it on hand having bought it for another purpose, a coarser mesh would do just as well.
Brazing rod is used to join metals by heat and can be bought at plumbing suppliers, use one that is not covered in a flux, it looks like brass rod. Any non ferrous metal rod of the desired diameter will do.
Plasticene is a trade name for an oil based modelling clay used by sculptors and model makers not to mention school kids. It's used as it does not wash away with the cooling water as potters clay does.
I use silicon carbide grit. Use a brass or copper rod of the desired diameter as the drill bit(brazing rod is suitable). Make a plasticene dam around the spot where the hole is to be made,add grit and water. Do not press too hard, replenish water as required and support the underside of the material being drilled otherwise the drill will break through leaving a ragged area around the hole. Repeatedly withdraw the drill to permit new grit and water penetrate to the cutting surface.Wear ear defenders and goggles.
Taylor and Bull discuss thermal expansion in detail in their book Ceramic Glaze Technology, including a simple series of tests using an electric oven and water to determine the resistance to crazing of a sample glaze.
Library of Congress Cataloging-in-Publication Data
Ceramics glaze technology
Includes bibliographical references
1.Glazing (Ceramics) 2.glazes. 1.Bull.A.C
TP812. T39 1986 666'.444 85-29700
It is worth chasing up your local library to get this book on loan as it also answers many other questions that crop up when you experiment with glazes.
My very first attempt at a tea pot. I had to share with someone who (might!) care.
Alice it looks remarkably like my first attempt and has the same fault - the spout is too low ! As I filled it up the water poured out. I still have it after 30 years to remind me to think things through, not that it always works but that is one of the attractions of ceramics there is always something new to learn. Mudlark