The colonization stage in incubator is completed. At this point you've already have spawn grain in order to move on casing.
This step is not necessary for getting psilocybe mushrooms, but it has several advantages. By mastering this skill, you will be able to increase your yield significantly and improve your skills in mushroom cultivation techniques.
Casing is not a complicated process at all. We wanted to describe it as briefly as possible, but then we went into explaining the basic principles of chemistry and mycology, which related to casing in simple terms. We think it will be useful to know for every cultivator.