I also use two safelights for RA-4 with #13 Kodak filters. One is near the ceiling and pointing at it, more than 7 ft away and the other can be mounted to point at the ceiling as well as away from it, at the paper, at about 5-6 ft. This is to facilitate making color photograms. Not a single cause of fog with either Supra III, Supra Endura or Ultra Endura when enlarging negatives, with the paper being exposed to safelights no more than 2 minutes total, as it's processed in drums. Photograms so far all seem to have pretty good whites that don't seem fogged, but, of course, YMMV.