Today I set about cutting glass as the first stage in preparing dry glass plates that I will expose in due course in my cameras. I have eight pieces of 2mm glass from old 8″x10″ photo frames, fifteen 75mm x 50mm glass slides and a dozen 75mm x 25mm glass slides. The slides are all 1mm thick.
For the photo frame glass I have 5×4 plate holders but frustratingly no camera yet to load with them. The Countess has a set of sixteenth-plate holders requiring 1/16″ glass so the larger glass slides will be cut down to fit these. For any left-over glass, my plan is to make pinhole cameras to fit.
I had hoped that the photo frame glass would be true 8″ x 10″ but in fact they were 7 5/8″ x 9 3/4″ so could not be quartered to fit my 5×4 holders. Plates for the holders are held top and bottom so need to be a full 5″ on the long edge. However they do not need to be a full 4″ wide. My solution was to cut one plate 5″ x 4″ and two 5″ x 3 15/16″ for the 5×4 holders and one 4 3/4″ x 2 3/8″ plate for use in a pincam I made for Worldwide Pinhole Photography Day 2014.
The 75mm x 50mm slides were trimmed down to the 2 5/16″ x 1 3/4″ needed for The Countess’ holders while the 75mm x 25mm slides were left uncut for use in custom pincams – they have a usable area of 50mm x 25mm.
Taking a tip from sheet film, to simplify identification of the coated side of the finished plates I cut a small triangle off the corner of each plate. When coating the plates I will coat the side facing me when I hold the plate in portrait orientation with the cutout top right.
The finishing touch was to rub off the sharp edges which I did with 240 grade wet and dry paper. The cut edges were all mostly ‘clean’ and unlikely to do any harm if handled carefully but I felt it worth rubbing them down anyway and they do feel better for it.
The next stage will be to thoroughly wash the glass and remove any surface treatments that would inhibit adhesion of the subbing layer. I plan to use sugar soap wipes for this, relying on the mechanical/detergent action to provide sufficient cleaning and keying. Time will tell! Once cleaned the plates will be coated in a gelatin and chrome alum subbing and hardening solution and dried, ready for coating with emulsion. This is as far as the process can be taken in the light. Once subbed, every ongoing process must take place in a darkroom or camera.