Whilst he was head of the Warner Brothers make-up department, he piloted several changes including introducing a description of shades of hair colour to use different types of make-up more appropriately. Whereas prior to Perc, studios described actresses simply as Blonde or brunette, Perc introduced a chart of thirty five shades of blonde alone. During the production of one film, Perc created a detailed latex hand for a close-up shot. According to Perc's brother Frank, the hand was so detailed that he was visited by doctors to study it and the process was adapted for use by the medical industry.