curdling of milk occurs in different ways with the help of chemistry let's try to understand. The methods of curdling: ACIDIFICATION:It may occur thanks to milk ferments that transform lactose in to...
See http://en.wikipedia.org/wiki/Kefir
They don't have a noticable odor, but you'll see soft spots, bruises, or spots of mold so it will be obvious.
It is because you can get ink poisoned if you keep it on you too long
he could make a potion that does bad stuff