Originally Posted by ThundercatRob
Is this only an issue with PVC, or can staining occur on hypalon as well?
Hyperlon is typically more chemically resistant as it is chlorosulfonated polyethylene. PVC being polyvinyl chloride can react with organic compounds more easily. I think it is easier for an agent to remove the chlorine atom from PVC. Hyperlon has about a third of those bonds as well as bonds with sulphur and I think it is that which makes it less reactive.
This is why with PVC you need to be a bit more careful with petrol spills etc.
I'd be very wary of using organic solvents to try and 'clean' the dye out as you could instigate a chemical reaction with the PVC.
Bleaching with vinegar or diluted bleach is the place to start but even then what you are doing is massively speeding up the bleaching caused by UV in an isolated area which is not ideal.
You could try leaving strips of cloth rinsed in vinegar or bleach on just the red area over night to see if that mellows the stain at all.
White dyes are about the weakest so I'm not sure you'd have too much joy. And this doesn't help the OP but RWD dye is hard to fix which is why we end up with pink shirts and pants but rarely blue etc. Avoid red material where possible but also soak stuff overnight to check but if anyone has ever had a car with white leather they may have learned that even the blue from denim can come out and stain it.
Salt water, sun and time may be the best way to temper the stain.