I had the same question so I wrote Michael's Customer service. ClaySmart is Sulfur Free. Below is their reply.
Hi Hugh!
After speaking with our Buyers, I was advised that our CraftSmart Plastalina clay does not have sulfur in it.
If we may be of further assistance, please feel free to call us at 1-800-642-4235. We appreciate your business!
Sincerely,
Ashley
Michaels Customer Care
Hi Hugh!
After speaking with our Buyers, I was advised that our CraftSmart Plastalina clay does not have sulfur in it.
If we may be of further assistance, please feel free to call us at 1-800-642-4235. We appreciate your business!
Sincerely,
Ashley
Michaels Customer Care
Hi Hugh!
After speaking with our Buyers, I was advised that our CraftSmart Plastalina clay does not have sulfur in it.
If we may be of further assistance, please feel free to call us at 1-800-642-4235. We appreciate your business!
Sincerely,
Ashley
Michaels Customer Care