What chemicals do you use?

[bhop]

I put weight on the bottom (clothespins as cosmonaut suggested) From my experiences, it's the brand of film that curls (side to side) and there's really nothing that you can do about it during the drying process. Ilford dries completely flat. Fuji dries mostly flat, and Kodak is almost always curling for me. The only way i'm able to get it flat is to squash it under something heavy for a few days. I don't like waiting a few days to scan, so I use some scanning glass from betterscanning. com on top of my film to squash it while scanning. I still have to put weight on top of the ends of those to get a flat scan with Kodak films. It's annoying, but it works.

As far as the chemicals I use:
B&W
Clayton F76 developer
Arista for everything else

Color
Unicolor powder kit for c41

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[O|||||||O]

I think the side-to-side curl has more to do with the humidity while it's drying than anything else.

I've had the same films dry flat or dry curled before. If you check on it every few minutes, usually you can see it curl as it dries, then flatten as it dries completely. You can see a 'wave' go down the film, and when it's completely dry, it's flat. Sometimes it seems like it never gets to that completely flat stage though.
End-to-end curl seems to just because of the film...
The side-to-side curl goes away after a few days to a week under some heavy books. End-to-end curl seems to last forever though. Efke curls BADLY (end-to-end) in 120, but usually dries perfectly flat in 35mm in my experience.

[bhop]

I know what you mean about the curl then flatten while drying, but as far as the humidity affecting the curl, I dunno.. for me Kodak curls 100% of the time, while the others don't, no matter the time of year or weather.

[O|||||||O]

It might not be the humidity, specifically - but I think it's something other than the film itself.

I've had the same films dry flat, or curl on me. I haven't really paid attention to what was different each time though...

[maris]

Here's an experiment I did with very curly Fomapan 200:

The negatives were a write-off so I soaked the film in a dilute solution of sodium hydroxide. This removes all the silver and emulsion, all the subbing layer, everything, and left only the film base. The film base was still as curly as before! All the curl was in the film base which had taken a set since it was rolled up tight at the factory. None of the developing, fixing, and washing stratagies made any difference because they did not address the cause of the curl. After 6 months in a plastic neg file under a heavy book the film base lies nearly flat. It had merely changed its set from bent to flat.

[dxqcanada]

I never had a problem with 35mm roll film.
120, because of the width, does tend to roll more during drying.
Kodak HIE 120 was very thin and would almost form a tube half way during the drying ... then it would slowly uncurl itself.

Once dry, I put them into sleeves ... and that flattens them.

[slackercruster]

You put 35mm film in a book to dry?

The way you dry 35mm film is you hang it up at one end with a weight at the bottom end until it is dry. Never have anything touching the film while it is wet.

Wetting agent for drying helps with spots.

[slackercruster]

Back in the day...I used to use Dektol for prints and D-76 for film. Extrachome E-4 and Agfa color with nitrogen burst. Tried dye transfer but it was too tough.

Now I only shoot digital and use inkjet printers.