100 years of Rosco colour Gel medium

From the LDI Expo;- 100 years of Rosco colour medium;-

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

However I cut my teeth on Cinemiod in pohmyland, which I remember was orginaly made by floating  the colour filter material in Bakers oven trays, hence the sheets were available in the tray size sheet mesurement - but that"s all another story!