Blue Wheatens will throw blacks, blues and splashes. If you want all blue offspring you can breed a splash pattern to a black and all the offspring hatched will be blue.
The splash pattern tends to leak a little bit of blue around the base of the tail feathers and occasionally in the breast of roosters in my experience, the dominant white is a clearer color but both are beautiful and once you have two splash pattern birds they breed true to color and you can set...
All good info! I happen to have a few wheaten, blue wheaten and splash patterned wheaten games so I thought I'd add a few pictures
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Wheaten
Blue Wheaten
Splash patterned Wheaten