Q–At the end of my 35 mm. roll of black-and-white film, I get white, streaky lines and, sometimes, dark spots. I develop my own film. Am I doing something wrong?
A–You have a double problem: water spots and static.
Water spots are caused by improper drying of film. When film is dry, these spots appear transparent on your film and print black when you make a print. The best way to eliminate water spots is to use a solution of Photo-Flo. After film is washed, dip your film for at least one minute in a mixture of Photo-Flo and water–usually a capful of Photo-Flo in a quart of water. Use a chamois to wipe the film before hanging it to dry.
The few extra minutes you take at this stage of developing will help you eliminate water spots.
The streaks are static electricity marks. These are caused by electrical charges on unprocessed film. Rewinding film fast in cold weather can cause static, and ripping film off the tape just before developing has also caused electrical static, which can streak the film and leave various shapes and designs on it.
Although static marks can occur on any surface bearing photographic emulsion, they are most commonly found on roll film. Among the things that can cause these marks:
— Friction caused by film rubbing against misplaced film guides or an improperly fitted pressure plate.
— Relative humidity greater than 65 percent or lower than 45 percent.
