A box with a black-white photo paper can be opened only in photo room in the dim light of a safe and comply with the conditions required until the end of fixation.
During the session, your hands should be clear, because you can leave indelible stains on it. Use gloves when handling chemical black-white photo paper.
Just a couple of tips: take a sheet of black — white photographic paper only in unexposed region, and if there will be spots, the edges can always be cut off without any damage.
Black — white photo paper on barytic -base requires particular care during development: it absorbs a lot of liquid and becomes severe, why can easily be broken, first of all, it concerns the large-format (30 x 40 cm and above).