OK, but try the combination of Metol-hydroquinone without sulfite. How much superadditivity do you get? Now add a very small amount of ascorbate and see what happens. While the thought of a developer without sulfite is repugnant to some, it is very handy to have a sulfite-free staining developer all of whose components are soluble in glycol. Granted, HC110 solved that problem with an organic sulfite, but it is not a staining developer. Sulfite in rather small concentration prevents staining in catechol or hydroquinone developers. It takes more to eliminate staining by pyrogallol, but it can happen. If the stain is not desired, sulfite added to the working solution will prevent it, and there is a wide latitude in the measurement of its quantity.
Originally Posted by Photo Engineer
A superadditive mixture of Metol or Phenidone with ascorbate is obtained without sulfite and is non-staining.