How did you know the vermiculity mixture was dry enough before applying the stucco?
If you haven’t fired the oven yet, fire it up (starting with small fires and gradually increase the length and heat). This should help dry out the vermiculite mixture. I did the smell test. Not exactely scientific but it made me feel important. Smell the vermiculite when firing the oven. If it smells musty, it’s probably still somewhat wet. If it doesn’t you’re fine.
