Ol’ Uncle Twee Cat’s Photo Esoterica, Pt. 1:
Are you interested in using old expired Ilford glass plate negatives? No? Oh. Well, I am. When you start trying to do this, you will find that they are surprisingly usable and more abundant than one would expect for a product which hasn’t been produced in about fifty years (the last of them were discontinued in 1973). But how to make good use of them? One method is to remove them from the light-tight packaging which has kept them usable and unexposed for many years and then balance them on the tip of your nose in room light. But this is totally ineffective and gives poor results (in fact, it should be said at the outset that photographic glass plates are sensitive to light and will be ruined if you open them in daylight – many people selling them on the internet seem not to realize this). What, then? What to do?
First of all, if you’ve found this, here’s the page you’re most likely looking for. Otherwise, read on. There is much useful information.
The stated speed ratings are provided in the old Hunter & Driffield standard, conversion tables for which are easily available. You can read about this film speed rating system on Wikipedia here.
Given that this system was superseded almost 100 years ago, and was not used in Ilford’s own literature after the 1930’s, I believe this document to be in the public domain, although I have not found a date of publication in it.
One might desire actual information on their original sensitivity and development. Ilford distributed this information, but it is not easy to find. I therefore provide you with this yellowed pamphlet:
Or, if you prefer, here it is as a .pdf:
By the way, there are some methods and techniques described here which seem outright dangerous. For instance, it describes how to use mercury as a bleaching agent. This is now known to be extremely hazardous to your health, although this was not known at the time of publication. I take no responsibility to any harm you may cause yourself be attempting these methods. Always follow the materials and safety precautions specific to any substance or product you are using and take all necessary safety precautions when doing photographic developing and processing of any kind.
Please note: I provide this information in the hopes of aiding other photographers interested in exploring alternative process and older photographic techniques. This information has not been easy for me to find, and I put it forward here in the hope of increasing interest in these photographic processes, which I find aesthetically desireable. I do not believe these documents to be under copyright due to their age. That having been said, if I am wrong and you are the copyright holder, please contact me and I will promptly take them down without protest. I do not intent to cause harm or in any way benefit monetarily. Kind regards, (T.C.)