The history of diffusion methods for film lighting

[Yi Wang]

Hello, anyone know anything about  how the diffusion methods and those diffusion equipments are developed through the history, I checked so many so called handbook for gaffer and grips, but none of them mentioned about it. I think it would be interesting to understanding how DP make the scene looks real with soft light in different time period. Any way to  access this mystery? Thanks!

[David Mullen ASC]

Early on, they used spun glass in frames, or large silks. But considering the powerful output of the lights used, the silks weren't used too often due to the fire hazard. Spun glass became replaced by Tough Spun (fiberglass).  There might have been some use of frosted glass for small lights, I don't know.  Heat was an issue in general and particularly with gels since they were made of gelatine. See:

https://spectrum.rosco.com/index.php/2010/11/the-first-100-years-from-gelatine-to-roscolux