Please refer to the following 3 links for reference to casing.
Almost ALL questions regarding casing, its purpose, and et cetera can be found in those links.
Casing has more scientific knowledge and write-ups than cakes do (since casing is a popular way by which edible/medicinal mushrooms are grown), and this technical, widely -published information should be examined closely before posting any questions regarding casings.
Shroomery Casing Teks
Getting the most out of your casings
What's the Matter With My Casing?
