Not quite coal, but...

I know you all held your breath waiting to hear the results of the first glaze firing.
And the verdict is....what happens at 1800 degrees Fahrenheit is trickier than I would have thought. The idea is simple enough: brush premixed commercial clear glaze onto already beautifully decorated pieces, pop into kiln, fire, and voila! A finished piece emerges.
Hah.
As I opened the lid, I heard a disconcerting and very odd pinging sound. Donning oven mitts, I carefully pulled out the top bowl. A shard of glaze about 1 inch long and 1/4 inch wide flew halfway across the room. Ping! Off fell another piece from the rounded edge of the bowl. I put the bowl down on my kitchen counter, and several additional smaller pieces popped off. I have read about this malady. It's called "shivering", and its about what I am doing about now. Wahhhh. There goes about 15 hours of my time. And in fact, after I completely unload the kiln, only two out of five bowls emerged un-shivered.
It's the old: What can I learn from this experience?
I guess I have learned that my new goal is to become a master (or mistress as it happens) of all that goes in and out of that kiln. My goal is to predict what will happen in there, not to rely on Luck and Hope, but on the convergence of knowledge and proper chemistry. Knowing that humans have been experimenting with blazing mud concoctions for thousands of years makes me feel a bit better that I haven't entirely conquered the process in two tries. And I have a distinct advantage in my day and age: internet search engines, keywords--Troubleshooting, Ceramics.