T2: i'm sure this has already been discussed...

...but i didn't have the internet access when T2 was released. i recently watched T2 again with my kid and it reminded me of something that bothered me back then--a film flub-- of sorts. it also wasn't mentioned in the book as i have read it as well.
my problem: Terminators (CSM 101) are covered with living human tissue to send them back in time, how could the T-1000 go through if he was pure "liquid metal"?
any explanations that i may have missed would be great! thanks!