Residual Lead In Kilns
Posted 04 March 2010 - 02:21 PM
I understand lead, when fired, gives off vapor and what not that effectively settles into a kiln making it unsuitable for use in firing functional ware. Is there any way to test a kiln for this? I have been looking for used kilns but many people are unaware of exactly what might have been fired in them. If lead is in the kiln is there a way to remove the lead, seal it or do something to the kiln as to make it usable again for food ware?
Also, do other toxic materials such as Barium and Cadmium result in the same leaching and adhering to a kiln causing it to potentially pass into other ceramics meant for food? Thank you for your time and help!
Can anyone weigh in?
Jennifer Poellot Harnetty
Ceramic Arts Daily
Posted 04 March 2010 - 03:27 PM
I'm not sure what it would take for lead to become vapor in a kiln (its boiling point is 1470 C), but one could use a lead test kit (the same kind that's available for testing paint) to see if a kiln is contaminated with lead. If it is, there is nothing I know of that will mitigate it. My suggestion would be to take the lead test kit along and test the kiln before purchasing.
The only way to actually test for whether or not lead would make it into your ware is to fire the kiln with a glaze that contains no lead or cadmium or any other material you don't want. Then have that same ware leach tested by a lab for each material you are concerned about. You would need to make the test vessels to the lab's specifications.
It is probably best to test the kiln before you buy it with a lead test kit, as Sherman suggested. But you can get rid of lead in a kiln by firing a container of nepheline syenite to absorb it. The container can be made of clay and should be about as big as the inside of the kiln. Put Nepheline Syenite into the container and then fire 270 degrees (F) per hour to 2000 degrees F. Hold for two hours. After firing dispose of the Neph Sy properly. This process doesn't guarantee that all of the lead will be absorbed so you should still have your ware leach tested by a lab!
Here is a list of people who provide these services:
Posted 31 March 2010 - 04:11 PM
Posted 02 April 2010 - 07:07 PM
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users