Holy smokes! I had no idea it would do that!Was it the first run with the cooktop? I'm a little nervous that mine will do the same. Has this happened to a lot of folks?
No, not my first use by a long shot. I do all my cooking on the cooktop. Don't be too nervous about using it.
I knew that HollowHill had her cooktop split, and so was a bit leary, and being careful not to add fuel to a good fire, which is what she had done, immediately before hers split. I don't think her stove was very hot either.
My theory is that both our stoves just had a rapid elevation in temperature in a very short time, as opposed to reaching any particular temperature. I was trying (unsuccessfully) to avoid that, after HollowHill's experience.
My son was not at all surprised about HollowHill's cracking, when I told him. He had installed my stove for me, and he said that the cooktop had way too much exposed surface to be able to take the rapid heating and expansion without cracking, because of the surface area the flanges on the bottom add to the cast iron cooktop lower surface.
So, my advice is not to start your fires with lots of little pieces, and to use caution in the rapidity with which you start your fire. Take a little longer to get the fire to cat temp, and close the air down rapidly in the process, just maintaining a good fire. I never leave the air fully open; close to about 1/2 as soon as I close the door, then very soon to 1/4, then on down slowly. If I want a hotter burn, I OPEN it again, AFTER the stove has already heated to about 325 soapstone top temp.
If your cooktop does crack, just cover it with the soapstone top (in other words, keep the cooktop covered). And, if you are leaving the stove unattended and have been cooking and have the cooktop exposed, close the soapstone over it before going to bed or leaving your home. Then, if the cast cooktop were to crack, it would be covered.
I don't think it will crack it that kind of situation. I really think it is only at the beginning of a burn.
That makes me think...I'm going to write to the PH owner whose PH overfired Sunday. If his cooktop is fine, that would supposrt my theory...unless he has a newer, shielded cooktop.