Water spots on film are a nightmare – there is no easy way to get rid of them once they are dry, and you can’t be sure you have non till the film is dry. Using washing agents and distilled water helps, but to remove the actual water from the film is a bit tricky. When you use compressed air you might blow dust onto the film, and when you use a film squeegee you might scratch your film. Instead, try the salad spinner.
This uses centrifugal force to push the water out, and since there is very little air in the spinner and it has a lid on most of the time, there is less of a risk of attracting some dust on the film. The film stays on the protective reel to avoid accidental contact and I never had any issues with film getting out of the reel. A few seconds of turning the crank is enough to reduce most of the water from the film to some tiny droplets that dry very quickly with no spots.
How to make one
A film spanner can be build with very little materials. I got my spinner from a local supermarket for about 4€. You need something to hold the reels – two 120 film cores work great –, some duct tape and tools to shape the 120 film cores.
Remove the end caps on one side of both cores, and then smoothen the ends a bit. The spools should have no sharp corners or loose material at the end.
Those two are ready to go.
Next get a 10cm / 4inch strip of duct tape and make a small cross in the center. You need that to push the 120 film core thru, with the remaining base against the sticky side.
You can then glue the core to the inside of the salad spinner. Make sure its far enough from the bottom that you can fit a film reel onto it.
Add the second core at the opposite side, and when you just spin one film put a empty reel on the other core so its not off balance – you won’t be able to spin it fast enough otherwise. I have a broken film reel that I just keep in there as a counterweight. If you have two films, you can balance it with the second reel. And don’t forgot to pour the water out once you’re done spinning your film!