I have been lucky over the past few years in that I've had no major problems with glazes, slips, clay, or firing. Knock on wood. So today when I unloaded my bisque and saw that my slip was flaking off some pots I realized my luck had run out... temporarily. I made a switch to a new white slip a couple weeks ago when I ran out of my other and didn't have the right materials to mix up a new batch. Well this new white doesn't jive with my flashing slip when they are layered. So I lost a few nice slab trays today. Tomorrow I will make more and on Tuesday I'll get the materials I need for my old white slip. Live and learn.