I used to work as a tech in a cleanroom environment producing a Class III Implantable product (and that is the only criteria I'm basing this response on as I have never looked into cleanroom definitions, guidance, etc). We did "gown up" as we went, before entering any controlled areas... scrubs in the locker room just outside the core--> shoe covers, hair covers in the gowning room before stepping over the magic line and then entering the core --> frocks and knee-high shoe covers in the gowning room adjacent to each manufacturing area. However, gloves were provided IN each manufacturing area and put on only when we were about to do any procedures that required them. But the caveat here is that we were not always required to wear them.