I have been using selenium as the last step during negative development to increase durablilty of the negative. I was told that it can be used to increase the contrast of the negatives too. I tried, but I don't see any significant result. Do you have any experience with selenium for contrast increase? How do YOU use it for this purtpose? What dillution? Do you rinse? How long to expose the negatives to selenium?
Haven't used it myself but have you seen Ansel Adams mention of it in 'The Negative'?
This produced about a one zone density increase in the highlights.