Let me share with you my experience with Agfa Aviphot Dia C. Found few boxes of 19?19 cm glass plates and very little information about it on internet.
A member of www.apug.org answered my general question about this material like that:
“Yes, I did a few enlarged slides with it, maybe 25-30 years ago. Treated it as any regular enlarging paper, it was around grade 2. Processed it in then my regular positive developer ORWO N120. Used glass cutter in darkroom to cut smaller pieces for exposure tests.
Beautifully crafted glass optical plates. Ideal for negative carriers, filters, contact printers etc. Most likely I have in my binders, sheet of paper with instruction that come with it.
Have fun with it!“
(thank you, Goran!)
Here is the leaflet I found in the box:
I do not have large format camera and thus had to cut the glass into 6.5×9 cm so it may fit my cassette for Mamiya RB67.
And that’s when the first problem came — the glass just didn’t let me cut it! I repeatedly tried to cut it with a glass cutter from local DIY store, but only got pieces like these:
It even didn’t broke where cutter was applied.
No other choice, I had to use the biggest pieces that could fit the cassette. And that explains the funny shape of the negative. Set my RB67 to F8 and made two exposures at 1/30 and 1/15 sec on a sunny-cloudy noon — according to my lightmeter that would correspond to ISO 12 and 6.
I used ORWO N-120 paper developer 20C for 5 min. as a starting point for the test. The result is here:
Then I decided to test it as a positive material to see what it would result to. Exposure was 1 sec at F/2.8 on my old Krokus 4 enlarger. Developed it with ORWO N-120 for 3 minutes.
The white strips you may notice is paper scotch tape. That was the easiest way to take the glass plate in and out — when wet, the emulsion is very delicate and my clips damaged it once before coming to this DIY solution. Here is a picture of the damaged plate on my light box
Also, be extra careful when washing the plates. I just let them stay under running water for 20 minutes. Then let them dry for 24 hours. After that you can touch the emulsion, carefully.
It looks very nice on a white background. Still haven’t decided how to frame these plates.
Another issue was scanning the plates. Since the glass is 2 mm thick, the image falls somewhere outside my Epson V600 focus area. So I had to “scan” them with my Nikon D7000 and a backlight flash.
Results are below.