Quote Originally Posted by Michael R 1974 View Post
It is also not clear how much Metol is in Microdol or Perceptol. Most people assume it to be 7.5g/litre because that is the most common amount used in D23. However this is not necessarily the case, and there were/are other versions of D23 with different Metol concentrations, such as 5g/litre.
I've never seen a version of D23 with 5g/litre Metol but then I don't use the Photo Lab Index data or most US books that perpetuate their misprints either.

All the major manufacturers have their specialist compounds that help prevent Dichroic fog, Agfa discovered and Patented their first in the 1930's a spin off from testing long chain non foamingwetting agents nto add to packaged developers. Ilford, Agfa, Fuji etc as well as Kodak hold Patents for these types of compound.