This is probably a daft question, but I've got a P44(?) (dark green material dated 1944) Bren gun spare barrel bag & parts wallet that has some sort of white powdery stuff on it. I've tried brushing it off with a stiff bristled brush, but it seems it's in the fibres. I'd like to wash it, but I don't want to damage it, so if anyone could give me some advice I'd be very grateful.
Cheers!