Everyone I ask about the strontium carb. gives me a different answer about it's safety. I would like to be sure it is food safe before I use the glaze on functional pottery. I would appreciate an answer from you. Thanks."
It appears that strontium carbonate could be the least of this glazes problems. Here is the chemistry of the glaze as calculated by INSIGHT:
Other articles on this site talk about balance in the chemistry of glazes and SiO2 and Al2O3 content are of primary concern in this regard. This glaze is extremely low in SiO2 (it is 1.5)(recommended minimum is 2.5), that leads to unstable glasses that leach. You could simply increase the silica in this glaze but it is so low that it needs to be increased to 30 parts in the glaze recipe to supply the minimum amount of the oxide SiO2! That is certainly going to affect the appearance of the glaze.
Copper is a destabilizing influence in many glazes. Often non-leaching glazes will begin to leach after copper is added. This glaze has lots of copper. Leach testing is obviously needed.
The recommend maximum for SrO is around 0.2, this has 0.27, that is likely too high (INSIGHT has built-in limit formulas that assist in determining minimum and maximum amount for oxides).
Perhaps you would agree that the writer should go back to the people who said this glaze is safe and ask them what they were thinking. We cannot guarantee that it is not, but certainly a simple leaching test is advisable. I am guessing overnight in vinegar will leach out the color at least.
Is Your Fired Ware Safe? Glazed ware can be a safety hazard to end users because it may leach metals into food and drink, it could harbor bacteria and it could flake of in knife-edged pieces.
Leaching Ceramic glazes can leach heavy metals into food and drink. This subject is not complex, there are many things anyone can do to deal with this issue