I have been told you have to load film holder in complete darkness why cant I use a darkroom safelight ??

B&W photographic paper is red/orange blind, so an OC safelight works.

Color paper has a photographic speed in the fractions of an ISO, so a 10w bulb behind a green filter will work in a color darkroom.

Black and White film is panchromatic (no real blind spot to a particular color) and much faster that photographic paper.

Because your safelight is only safe for photographic paper, not for film.
A very long time ago, plates/films were blind to red so it was easy to load/process them in subdued red light.
Today's film is sensitive to all colors so must be handled in total darkness.


And Les has been faster than me !

thank you very much

There are a few Ortho films out there, such as Ilford Ortho Plus and the few remaining graphic arts films, that can be handled with a red safelight. As mentioned, the Panchromatic films need total darkness. Modern color films and papers, same thing, no light whatsoever. Loading holders in the dark is a snap if you don't pull the slids all the wy out. Pull all your slides 3/4 of the way out before you go dark. Remember that the film emulsion faces you when the notches are on the upper right corner, or lower left if you want to be different. Just check carefully to make sure the film is under both side rails before pusing the slide in. Very easy. Good luck.