Film negatives are typically flat squares when they are developed. The flatness of film negatives is critical to enlarging them to photographic paper or scanning them. If your film negatives are not stored properly or a problem occurs during the developing process, they may curl at the edges. You must flatten your film negatives to avoid problems when viewing or working with them.
Fill your clothes iron with water and turn it to the cotton setting. To uncurl your film negatives, you need both heat and steam from your iron. Lay your curled film negative as flat as possible against your ironing board, then lay the piece of cotton cloth on top of it.
Iron the cloth on top of the film negative for 10 to 20 seconds. Press the water button on your iron to release steam and keep the cloth moist. Iron evenly and steadily on the cloth to avoid burning the film.
Remove the negative from under the cloth and quickly place it into one of the square pouches in your film sleeve. Ensure that the negative is not curled when you place it in the sleeve.
Place the film sleeve under two heavy books. The weight of the books keeps the negative flat as it cools down and loses moisture.
Keep the flattened negative in a film sleeve whenever possible. Improper storage of film negatives could cause them to curl again, possibly warping the image.
Do not overheat your film negative when ironing it. Too much heat could damage the image.