I found Pam Spray Cooking Oil works well as a release agent, Mineral Oil works good, I've also used Vaseline but you have to be careful not to get it too thick. Using Murphy's Oil Soap is a good idea I haven't used yet but will give it a try. Regular Dish Soap didn't work very well for me I had sticky molds.
I found some Utah deep red native clay that fires to a cone 5. Straight off the hill, screened once it throws wonderfully up to 18 inches without grog. Is there a quick and easy test for lead? I would also like to explore using the clay as a slip glaze. What would I add if the glaze test appears under fired or over fired at cone 10?