Making digital negatives for contact printing?

[ozy82]

I would like to produce digital negatives on photoshop to use as contacts in the darkroom. Mostly out of curiosity.

I've had a couple of goes, but the photos are slightly blocky in areas of light, low contrast. There are also some blocks of grey that stick out. This is after straight forward inverting a black and white photo, printing via laser printer onto acetate, then contact printing in the darkroom.

Searching around the internet I keep on finding references to a book by Dan Burkholder, but nowhere has it in stock, and I just want the basics, not a whole book! Could someone please explain to me the basics. There seems to be a lot of stuff to do with curves, and also I've seen photos of these negatives and they're all red. What's the best photoshop method for producing something like this?