Case in point : a friend with a quantity of unmounted slides,70's era bvious fungal damage most visible on the surface in reflected light,but does not appear to have damaged the image itself. I cautioned him against using anything water-based,but that's the limit of my expertise. A product called PEC has been suggested.I also have on hand Edwal Film Cleaner,and some high purity isopropanyl alcohol. Checked the threads on this before posting- but any helpful update would be welcome. The film was probably processed in Australia : does anyone know if a protective lacquer was used at that time ?