Cleaning 35mm slides with heavy mould infestation


New Member
Feb 7, 2022
I just received some old slides from about 20 years ago, and fungus/mould has eaten into many of them.

Photos (warning: gnarly-looking fungus):


I have some PEC-12, but I noticed, when I tested it on some less important slides, that it doesn't seem to fully remove the really bad infestations. When I use 75% isopropyl alcohol on those areas, I have taken the emulsion off, which I’ve read is because the mould makes the emulsion water-soluble, and so it dissolves in the 25% of the solution that is water.

Will simply going over the white clumps with the PEC-12 be sufficient to kill the fungus and prevent further degradation, or will the infestation survive inside the clump and spread again later? I'm resigned to the damage the mould has already done, and just want to prevent further degradation and the infection of other slides it will later be kept with.

Any other advice on cleaning slides will be greatly appreciated as well!

Last edited: that you need to put on your professor cap and read this article. The key word is chitin, it's the cell wall of the fungi but do note there are many species of fungi. This method is not 100% foolproof but has been documented at varying success. Of course it up to you to experiment.

Method: Freeze the slide in freezer. Article does not say how long but I reckon just a short while. Then take slide out and immediately moisture forms on slide. Just use cotton bud to brush off fungi. See photo 2 ,3.
It explains why this method "work"
very scientific and cheem. I was surprised as well. Good luck.

Happy reading.

Ps pec12 is a waterless cleaner and it claims can remove mildew whatever that is. But generally it removes oil and dirt with varying degrees of success. The article did mention pec12.