Quote Originally Posted by RalphLambrecht View Post
I was in Howard Bond's darkroom once, and he has no darkroom door at all. The whole entrance is designed as a light trap. You walk around a double corner in which the walls are painted flat black. It is open and yet light tight, which is great for a teaching darkroom where people can go in and out without disturbing the session. It takes some floor space but is very convenient and offers a lot of ventilation.
The Evergreen State University (Olympia, Washington) has a great darkroom with about a dozen enlargers in use all the time... and no door. They do hang a black felt curtain in an entrance configured almost exactly as Bond's entrance is described. I suspec the curtain is overkill but perhaps not.

Light does not bend around corners unless by reflection or an appropriate shaped lens. Painting the entrance flat black largely supresses reflection but not entirely. Perhaps this is why the university uses the black curtain.