black is spread blue... spread can "cover up" the pattern of the bird.
spread blue "black" hen crossed with blue bar cock
most likely, you will have a 50/50 chance of spread blue baby and a patterned blue baby. You will NEVER get a red baby out of this pairing.
more in depth information:
your blue bar cock is an easy bird
blue/blue bar/bar (very small chance of brown or barless)
now your spread blue hen can be so many different things
blue/* (spread/spread or spread/wildtype) (bar/bar or check/bar or check/check)
so your hen is really the deciding factor to what the baby will look like... since the cock is only passing his blue gene and bar gene to all his babies. but then hen could be passing on many different hidden genes.
i can only hope you understood a quarter of that... haha it really is too much information.