Having Glazes Tested for Extractable Metals

Having your glazes tested for extractable metals is quite easy and inexpensive. I am now aware of only one testing laboratory that will provide this service for individual potters or for large organizations--Brandywine Science Center, Inc. (BSC) in Kennett Square, Pennsylvania--at reasonable cost.

Here are the steps to follow:

1. Make a small cup. The cup can be most any size; however some of us have agreed to a standard size to make our results more consistent and comparable. Unless you have a special reason to use a different size, I recommend you throw cups that are straight-walled cylinders 4 inches (10 cm) in diameter by 3 inches (7.5 cm) tall (wet dimensions). This size cup can be thrown from 1 lb. (454 gr.) of clay by someone with modest throwing skills. An experienced thrower can probably do it with 400 grams or less. Dry and bisque fire the cup, glaze it and glaze fire it at your standard conditions. Make sure the glaze completely coats the inside of the cup. I usually put a cone pack right next to the cup so I will know exactly what temperature it saw during firing.

2. Send the cup to:

	Brandywine Science Center, Inc.
	204 Line Road
	Kennett Square, PA 19348
	Phone: 610-444-9850
	Fax: 610-444-4080
	Email: bsclab@brandywine.net
	Web site: http://www.bsclab.com/
	Questions: Call Mike

3. Enclose a letter specifying what to test for and payment (U.S. funds) based on the following fees. Note that these fees are subject to change and you should check directly with the lab for their current fees.

	BSC
	Extraction: $5.00 per sample
	Testing: $13.00 per metal (lead is $18.00)
	Pay by: Check or VISA/MC

There is an extra charge if you want your samples returned; call them directly to determine the charge.

 

4. If you send multiple samples make sure they are well labeled so you will know which result goes with which sample.

5. In 1-3 weeks you will receive a written report on your glaze. BSC is certified by the Pennsylvania Department of Environmental Protection and the Delaware Department of Health and Social Services.

6. While there is no requirement that you send the glaze composition or firing conditions, I would appreciate it if you would. If you are willing to share that information (and state so in your letter to them), BSC has agreed to give me a copy of your data to aid my research. I am posting the results from glazes I have tested as well as those sent to me by others

7. If you want advice on what you should test for, Email me and I'll be glad to offer an opinion.

A last note: I have no financial interest in BSC; they do give me outstanding service for my own glaze testing.

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Copyright 2008, John Hesselberth. All rights reserved.