Opening stuck film cans
Sometimes old or rusty cans can be quite difficult to open. It is often helpful to tilt the can to a vertical position and gently tap the rim of the lid against a hard surface, as you might with the lid of a jar. A variation on this is to hold the can firmly against your side and using the edge of your hand 'chop’ the lid of the can. Another method is to wedge a screwdriver or similar instrument between the lid and the bottom of the can to prise them apart.
In considering which method to use, the likelihood of damage to the film should be considered. For example, if you think that the film is loosely wound inside the can then any technique that will cause the film to move around is probably not a good choice as it will increase the risk of damage to the film by scratching. Conversely, if the film is very tightly wound and packed into the can then using a screwdriver to prise the lid away may also damage the outer edge of the film.