Nancy, I do like throwing with Bmix, but have had cracking issues in the past, but not problems with the handles falling off. However, I have never thrown, trimmed and fired all in one day. Maybe it's just because my climate is different, but it does seem like you are putting things in the kiln rather quickly. I had my first explosion ever during a bisque a couple of months ago. I knew I was taking a risk....the mug was still just a bit cool to the touch. Lesson learned. But like Mdobay said, sounds like it isn't the clay, the pot didn't have enough time to dry.
Usually I don't throw, dry and bisque in the same day. Last holiday when I was making a lot of mugs, I'd dry them for a few days under plastic, then another day out and Crack!!! The handle would separate from the mug! I was redoing almost every handle. Is there an ideal temp to dry BMix at maybe? My basement is cool, but my studio is warm. I've used both.
Nancy, It's pretty funny reading this thread about bmix. Bmix seems to be a temperamental clay. Your experience with the handles is exactly my experience with the cracking issue with bmix. carefully dry it and before I can get it in the kiln, crack! And I agree with your drying experiences also. Doesn't seem to matter, cool, well ventilated, warm, covered.....it still cracks. However Denice didn't have good luck with it for handbuilding, but that is the one place I have been able to use bmix. It makes lovely trays, vases, tiles, etc. What is it with good ol' bmix?! When I use up this last 100 pounds, I probably won't buy more. I have had much better luck with a mid fire porcelain.