Basically what they said that in this cross, none of the birds will be mottled.. but mottled can be a little weird, such as showing up on young(cross) birds which then lose them at their first adult molt, and maybe show it again when they're really old.
However.. if your goal was blue mottleds, simply breed those cross chicks back to any pure mottled. Sex of either parents doesn't matter much so just go with the best type birds to use for breeding.
You'll get a few blue mottled chicks from this cross. Other chicks will be pure black, pure blue or mottled. Many of the pure blacks and blues will be carrying the mottled gene though- not all, just most.
Then if you keep the blue mottleds and breed those to mottleds again you are set for a pure breeding mottle strain that throws blue mottleds too.
Basically the birds have to be pure for the mottling gene to show it more consistently.. blue is the ridiculously easy part.
