Howard Lester wrote:
Totally dark. I think the only film with which you can use a light bulb (a
red one, specifically) is orthochromatic, which is not red sensitive.

Kodak used to sell a dark green filter which could be used only for a
few seconds after development was half complete. I think it was designed
for panchromatic film, not color.

A friend of mine had one in his darkroom, which was really the unfinished
area under a staircase, which had a toilet and sink, so it was sold as
a "1/2 bath". The light leaking in from the other room was brighter than
the safelight.

After that I never used one myself, and just did it by feel.

I know the OP asked about color film, I'm not sure it would matter.
The timing and temperature is critical not only for density but color
balance.

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379
"Owning a smartphone: Technology's equivalent to learning to play
chopsticks on the piano as a child and thinking you're a musician."
(sent to me by a friend)