I mix and develop glaze recipes for midfire stoneware (fired to 1220°C). The colorants in pottery are mostly iron, copper, cobalt, tin, titanium, chrome, and a few other transition metals. Many of these materials are somewhat toxic in the raw form but safe in the finished work. These colors usually make up less than 3% of a glaze recipe.

Vanadium is a colorant that potters seem to fear without good reason. I find resources such as MSDS sheets to be very unhelpful on this subject.

The heart of my question is: in your humble-I-am-not-going-to-sue-you opinion, is vanadium (specifically tin-vanadium) safe enough? How about relative to cobalt?

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    $\begingroup$ See this abstract on Pubmed for information concerning the toxicity of vanadium and its salts. The net of it is don't inhale: "Most of the toxic effects of vanadium compounds result from local irritation of the eyes and upper respiratory tract rather than systemic toxicity." $\endgroup$ – Todd Minehardt Jul 12 '17 at 19:34
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    $\begingroup$ I'd point out that there are two different toxicity problems, first to the potter and then to the user of the fired pottery. $\endgroup$ – MaxW Jul 12 '17 at 20:38
  • $\begingroup$ Yes, vanadium is safe enough relative to cobalt. $\endgroup$ – Ivan Neretin Jul 12 '17 at 20:40
  • $\begingroup$ Thank you. Everything with mixing dry glazes is a respiratory hazard so that isn't a new worry. $\endgroup$ – Matthew Potter Jul 12 '17 at 21:02
  • $\begingroup$ I'd be more worried about what sort of toxic species might be released when the glazed items are fired. You'll breath all of that in. $\endgroup$ – MaxW Jul 14 '17 at 9:09

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