Safelights can of course be tested. Make a proper print exposure of a picture with lots of bright highlights scattered throughout on half of a sheet of paper (other half blank), taking measures to expose it to the safelight for only the briefest of seconds, if at all.
Then put the paper out visible to the safelight, but blocked for a small strip at the edge at right angles to the split between test print and blank. This piece is to have pure white in the blank and pure white in the highlights of the print half. Then step across blocking more and more of it in 30 second intervals up to about 4 minutes (8 strips).
Develop with the safelight mostly off except for putting in and taking out of developer. Stop and fix and wash per normal. Evaluate your safe exposure to the safelight.
A good enlarger timer is arranged to turn off the safelight during print exposure (you might have a long set of dodging and burning to do). Large darkrooms can have a safelight in the enlarger area, and a separate safelight in the tray area, perhaps with a foot switch so that the safelight can be off during the bulk of development, if safelighting is an issue for that paper & light combo.
Last edited by Monito; 09-12-2011 at 09:50 AM. Click to view previous post history.