PC acetate filter cleaning???

[LabRat]

Hi,
I am restoring one of those old 4X5 steel lunchbox sized contact printers (for proofing in a darkroom without space for an enlarger or light source) and proofing with old MG RC paper that's a little flat... This paper needs a #3 or #4 MG filter for a normal #2 contrast (I have a large box of this paper I'd use up for proofing), and I dug out a few old Kodak Polycontrast acetate 150mm square sheet filters, that I can cut to place under the diffuser... The filters are good, but dusty with mildew dust... I know you can't clean gelatine filters, but I think I remember that acetate filters can be washed??? I think Kodak once said they can, but I can't remember...

Thanks,

Steve K

[Ted R]

The acetate base probably doesn't care but anything with a gelatin surface should be treated as delicate. Gelatin softens in warm water so it may be best to use cold. Also consider using IPA (isopropyl alcohol) which is good for removing organic junk. I would test a small corner first.