Blue Sex link project
A blue Orp over a barred rock will make sexlinks. Half will be black and easily sexed, the rest will be blue and not very easy to sex. I tried this last year with a Blue Ameraucana over Berred Hollands and it was a total failure, couldn't sex the blue chicks at all, though they did turn out to be great blue egg layers with pretty blue feathers. The sex linkage part was just not useful at all. This year I'm using California Greys instead of Barred Hollands (mostly for better egg production, CG's are much better layers). It seems to be working a little better, I am finding some chicks with white head spots. Time will tell if the "females" I'm keeping really are . . .
That's why I suggested Lavender. When put over a barred or cuckoo (both are black base) will give all black offspring for easy head spot identification of sex. The black females will be split to lavender so can be used in the lavender breeding to improve color.