Quote Originally Posted by Thomas Bertilsson View Post
Your geographical location makes a huge difference, because it's humidity related. I live in Minnesota, which has some of the biggest differences in humidity in the world, comparing summer to winter. Bone dry like the desert in the winter, and often 90% or more in the summer.

In the summer my negatives dry flat, and in the winter they don't.
Thomas is correct and that is what I experience in Finland. The relative humidity of the air in the room when drying the film needs to be as near as possible to 50%. In winter in Finland, the dry air brought into the house and warmed up to 20c has a relative humidity of 20 to 25%. The film curls like hell.

Flattening the sleeved film under a pile of books after it is TOTALLY dry can improve it a lot. Beware that the film can get damaged if still slightly damp, because the pressure "embosses" the texture of the sleeve into the emulsion.