This year I read a paper published in 1938 regarding how gels are named and numbered. In the year prior members of the Illuminating Engineering Society (you've heard of them, the IES founded in 1905 in NYC) had approached the esteemed color researcher DB Judd to solve the problem of how to name or number gels in a way that was simple and described the properties well. That way transmissive filters from different companies could quickly and easily be compared. Judd correctly determined that...
Designation of Filters for Theatrical Lighting - 1938 DB Judd
Designation of Filters for Theatrical Lighting - 1938 DB Judd
