Ansel Adams is always a good place to start and to go back to for grounding when we get carried away by fancy stuff.
Originally Posted by DimasShishkin
To get a pure black, you need to have sufficient development time for the print. The development times given by manufacturers such as Ilford for their MultiGrade paper tend to be oriented toward production darkrooms that want to print quantities of pictures quickly, often with processing machines. Thus Ilford MG has accelerators in the paper and will come up very quickly in the developer tray.
But be sure to give sufficient time if you are making the highest quality prints. One way is make a funny kind of test strip. In the darkroom with safelight on, mark a strip of paper into about 5 to 8 segments with a pencil. Then expose the whole strip to white room light for a couple of seconds. Don't overdo it because you don't want tone reversal. Then feed the strip into the developer, segment by segment. Give the first segment 15 seconds and then feed it in further to cover the next segment. Give each segment 15 seconds and give the last segment a whole minute (60 seconds). You should see a difference between the last segment (60 sec) and the next to last (75 seconds). At some point you won't see a difference, and then you will know how long to develop to get your maximum black.
Then adjust your exposure to get a touch of detail in the brightest important highlights. Just a little bit of detail where needed so that there are some pure white unimportant highlights.
Adjust your contrast as needed to get pure blacks. For some negatives, my first guess at contrast is not good and I have to go back and make some more refined test strips at the new contrast.
My first test strip is often rough, like 10, 15, 20, 25, 30 seconds. Then the second is more refined around the
best time, say 16, 18, 20, 22, 24 seconds.
I'm going to design and build a test strip box which will take a 4x5 sheet of paper (10 x 12 cm) and expose 12 little rectangles in a 3x4 matrix by moving the paper underneath the opening. This way I can expose four timings and three contrast grades of the same part of the negative when I'm making 8x10 (20 x 25 cm). I might make a bigger one for an 8x5 sheet (20 x 12 cm) for bigger prints (say 11x14 or 16x20, say 40 x 50 cm).
I'm getting back into printing after many years absence and finding that there are always new things to learn.