I just processed a roll of color film and somehow there was sand in the bottom of my tempering bucket and I used it to rinse out my film. Woops. It's now embedded in the film. I tried on an unexposed area to remove it by moving my finger across the film. It worked somewhat. How do I remove it with minimal damage? Also I tried cleaning film with a tissue and film cleaner and apparently scratched it. What else can I use?