If you have a rooster with mottling, you might try him too.Yes, I'm gonna be crossing my color changing hens to solid, & barred roosters, Malays, Project Wheaten Crele Orpington, & Heritage Plymouth Barred Rock.
Mottling is definitely one thing that can cause a chicken to get more white with successive molts.
Getting some chicks with a known mottled parent, and without barring, might help sort out part of this genetic puzzle.