Ron (PE) say's Dye bleach.

This is where the dye's already present and is destroyed during processing,

In a normal dye coupler process the dye is created as part of the development process, Ron (PE) has suggested a method for this as well. But as he's said you need more than hand coatings.

Getting specialist chemistry has always been an issue, you need to be a company these days with an account to get some items.