Thank you for interesting read, but still this paper doesn't answer my question. It only gives me approximate dates, and I really want to know when the first test cards, be it 18% gray, shirley or any other card or not card were used. I read through Barry Salt's paper but couldn't find any data, just information on unification of major hollywood studios systems concerning exposition. I believe the dp's just shot test rolls, or based their calculations on previous experiences.