Hi all, in a local charity shop I recently stumbled upon a large Cibachrome print from 20yrs ago by one of my favourite landscape photographers. I have a bit of work to do remounting it properly, and clean and refinish the frame and glass, but the print itself is in great condition EXCEPT for what appears to be a small patch of filament style mould/fungus (similar to what you see on old badly stored lenses), you can feel it on the surface of the print, although under the glass of the frame it's not immediately visible.

My first thought would be to dip a cotton swab in isopropanol and gently see it it'll wipe off. However I don't want to put any sort of solvent on only to find it melts the emulsion or anything weird like that. So before I ruin a perfectly good print does anyone have any tips for what type of chemicals are safe for attempting this sort of thing on Ciba/Ilfochrome prints? All cautionary tales greatly received.

Thanks
Dave