we made donuts every day- usually a huge batch of dough and then separated it into the makings of all different kinds. started at 3:30am, and finished around noon (sat/sun in high school).
not sure what kind of grease was used- it came in giant plastic buckets, though, and was probably some kind of basic lard melted. i mostly did the actual frying/turning/lifting out of grease vat of the donuts and then the icing/glazing.
only with freshly fried ones, dripping with ultrahot grease. the icing was too sticky and left evidence. but a good friend of mine (who i'm still friends w/ and see often) worked the counter and she'd pass off any "tainted" donuts to certain bitchy consumers.