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burnishing and pit firing - terra sig

updated mon 18 apr 05


Vince Pitelka on sun 17 apr 05

In resonse to Cindy's post, you can find my article on terra sigillata at

You can find an appropriate hydrometer for making terra sig at

Be sure to paste in the entire link. The one specified "WLS42035-A" is the
right one - it has a specific gravity range from 1.000 to 1.222, which is
exactly the range you need for terra sig. A normal glaze hydrometer
purchased from a ceramic supplier does not have nearly the sensitivity, and
will not work for terra sig. As you can see, the price of $10.25 is very
reasonable, but these instruments are very delicate, so I would purchase at
least two. When I bought my first glaze hydrometer thirty years ago, I only
got one, and it broke on the third or fourth use. I didn't realize how
fragile they are. Next time I bought two, and had them both for many years.

The length indicated on the website for the above hydrometer is inaccurate.
It isn't more than 8" or 9" long. It still helps to have a tall thin
container like a graduated cylinder for measuring the specific gravity.
- Vince

Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111,