Masking contact prints
I last contacted the list with some sharpness problems when contact printing (Pt/Pd). My father has since modified my contact printing frame and produced more pressure. I noticed the other night that when printing 5x7 negs for around 5-7 minutes there were no soft patches at all, but by the time I'd gotten to the desired exposure I was at 9m45sec and was getting soft stripes. I figure it was to do with the heat build up and i'll try building up the exposure incrementally with breaks to let the heat dissipate.
Anyway, my question to the group is as follows. I'd like to know peoples ideas for best way to mask the neg during exposure to prevent black borders. My method which is failing was to cut a 5x7 rectangle in a piece of black card and to stick the negative into this card using ruby-lith to not only hold it in place but to mask the shoulder/film edge etc and create a clean rectangle. The thickness of the card is about equal to the film and thr uby-lith was on the glass-side.
I intend to exhibit these images and wish to present them un-matted, on 11x14 paper. What's happening is that next to the print edges, about 1mm away, I am getting sporadic short lines of exposure that looks like it's refracting through the film-edge or something.
As stated I want to exhibit these unmatted and would like to know if anyone has a better way of masking these negs accurately?