Help! Silpoly question

I have some gray 1.1 gray silpoly and some black .93 membrane silpoly from RBTR to make a bivy. I haven’t worked with silpoly before and I can’t tell if there is a “in“ and “out“ to the material. Does anyone know if there is, and if so, how to tell? Or whether it just doesn’t matter?

I was hoping to make the bivy this weekend but forgot to call RBTR in time.

Thanks!