After last weeks dry run I realised that the 300W stage flood I got from Ebay was too directional. I decided to go back the 150W halogen floodlight I used last year:
The problem with last year was that I sandwiched a green lighting gel inbetween the lamp housing and the class cover. Although lighting gel is rated for high temperature operation the gel I used ended up like this:
The bit in the middle was blackened and really attenuated the light output of the lamp.
Hoping that this was caused by thermal conduction from the glass plate, I made a steel
gel mount to mount the gel in front of the lamp with a 10mm air gap between the glass and the gel:
It's a pair of steel plates that bolt together, sandwiching the gel between them. It then mounts
on top of the floodlight:
I ran it for 3 hours without any obvious degredation to the gel.