I have bee troubled with drying marks on my 35mm B&W negatives recently. I am working on a solution, but have some affected films I want to print. I bought a spray of cleaning solution which is meant for cleansing skin and equipment by professional manicurists. It is mainly Isopropyl, with some additives including a blue colour . I couldn't find straight isopropyl alcohol. It works when applied to the film base and evaporates quickly. Is the alcohol likely to cause long term damage? Thanks, Alex.