When making low temperature cheeses, whey will spill out from pressing or hanging curds. However, it is probably easiest for most people use the whey from making kefir or yogurt cheese, or the soft cheese of the Fundamentals eCourse. You can also use store-bought plain kefir or yogurt, as long as they contain active cultures.
It is normal for a few milk solids to slip through the cheesecloth with the whey. Over time, they can get moldy floating at the top of the whey. Strain them off as necessary, and usually the whey is fine. It should smell fresh; let your nose be your guide.
How To Get Whey https://traditionalcookingschool.com/food-preparation/recipes/free-video-whey-what-it-is-how-to-get-it/