I've helped set up a darkroom at the local university.
My (cheapskate, but reasonable) choice for safety lights had been to re-install a pair of old 5.5" round Kodak safelights that are lying around. I suggested just to get OC filters for them (they currently have a OA and 1A in them) and run them with e.g. ceiling mounted string-pull switches.
Anyway, there are currently bright red fluoros intalled instead, which turned out to fog the paper (enough said)
So, to remedy the situation, the electrician suggested this solution:
Has anyone used these filters? Which type?