Never give up, never throw away the half prepared materials, half finished photos even if you think they won’t work. The unsuccessful materials are the best thing to practice and make test on.
This is how I acted when an attempt to repeat my last emulsion failed abysmally. It was great the first time. Well, it was ok the first time, now there was no speed, no contrast, abysmal failure. It was not an accidental failure either; this is what invariably happens when you try to improve to many things, to make too many changes at the same time. At least I suspect what went wrong.
Anyway, I had a small batch of emulsion that was useless for absolutely anything except for tests and experiments. To be more precise, it was just perfect for an attempt to improve the properties of an emulsion by means of chemical sensitization. Yes, I know. It is not the brightest of ideas to try to improve the properties of emulsions made with active gelatins by means of chemical sensitizing. On the other hand, this particular batch of emulsion couldn’t get much worse. A few calculations to get a good guess at the best amount of sensitizer. To be honest I expected that even this tiny amount will fog the emulsion completing its destruction. A few hours later, the first surprise. A quick sensitometric test suggests that the emulsion has actually been improved considerably. With the plates coated, all one can do is wait for them to dry.
Monday morning came and with it, the first test. I tried exposing the plate at 3 ISO; that was more than a couple EV above the original speed. The plate placed in the developer develops almost instantly. Some twenty seconds it is clearly too dark. Test number 2; this time at 10 ISO, At the back of my head I still have the original appearance of negatives made with this emulsion; muddy, devoid of contrast, thin, useless.
After a minute in the developer I can see how much has changed. First of all the image is still overexposed. Not drastically so, but still exposed which indicated an even higher speed. Secondly, it can’t possibly be the same emulsion. Not only is the speed many times higher, but the image is clear and the negative, if anything, too contrasty. And this is the moment when I start regretting the fact I was so careless about coating this emulsion on plates. Another lesson. If you do anything, even if you expect nothing, do it the best you can.