This is a short, 11 page workshop handout, which I have had a high number of requests for so I am posting it for a modest price. It is from a workshop I did in Tucson and Jon Anderson helped me write it up neatly (which is not always the way I do things!) . It describes a combination of various glazes with stains that gas off and produce spots at cone 5. One glaze is an Oil Spot ( contain iron oxide) but others are mason and inclusion stains. If you fire it much higher it can cause spots to melt into the glaze.
I have 7 recipes and a special firing cycle call Slow and Low and all are include in the handout. There are also a bunch of possible variations with other stains you can try. Enjoy!