Expert: John Franceschini - 3/18/2010

Question
I am an art teacher so I have a basic familiarity of lead based glazes.  However, I have two easy questions for someone like you....

If you are unsure if a piece of ceramic has a lead based glaze on it and it gets put into the microwave, would it cause it to spark or smoke due to lead frit or particles?

Secondly, I have a candle warmer that is made of ceramic and is glazed.  -IF- that warmer has lead based glaze on it, what are the implications of warming wax in the top of the warmer and will that filter lead based fumes/toxins into the air?  I know that lead can leach it's way into food, but I wasn't sure about it being released into the air when heated.  The warmer is being heated to a temperature of approx. 125% by way of a 25 watt bulb.

Thanks so much for any info or insight into this!

Answer
Hi Stephanie

Dont know about the microwave question- at the risk of being politically incorrect you may have to try it to see for yourself- but do it carefully!!!!

The Lead glaze should have already been heated to a very high temperature to sinter the glaze and so the likley production of lEad volatiles during gentle heating seems unlikely. Again- I wouldnt go doing it all the time and exposing myself unduly- but occasional usage under controlled conditions should be fine.