I work in total darkness when tray developing film or working with color paper. I've had even small
red LED's fog shadows with certain film. My LED timer is now UNDER the sink where the film can't
see it at all. For black and white paper, I use an old Kodak barrel safelight, but it's connected to a
rubberized (shockproof) footswitch, which I momentarily step on when needed. I've heard plenty of
stories about Thomas safelights fogging things.