Don't confuse a grain to grain transfer with innoculating pasteurized substrate.

In G2G you're putting colonized grain into a jar (should be sterile - at least that's what you're shooting for) of other grain that will stay as sterile when you put the cap back on after the transfer.

When innoculating substrate, you're mixing that grain spawn with a pasteurized substrate (straw, coir, poo, etc) and then leaving it in an environment that will not be sterile (monotub, etc.).

I do G2G transfer in a still air box and rarely have any issues. Doing it in front of a laminar flow hood would be optimal.

Reading up on sterile procedure will clear up a lot of these type of questions :thumb_up: