The Andalusian Blue gene (Bl) is incompletely dominant and does not breed true. One copy of the Blue gene (Bl bl) will dilute black pattern to a slate blue color. When blue males (Bl bl) are mated to blue females (Bl bl) the resulting offspring will be approximately 25% black (bl bl), 50% blue (Bl bl), and 25% splash (Bl Bl). Splash birds are homozygous for the Blue gene and their unique coloration is a result of the further dilution of blue pattern due to a second copy of the Blue gene.
A Frizzle bird should always be bred to a smooth feathered bird, and statistically speaking about half of all of their chicks should be Frizzles regardless of color.
Here is a color calculator that I like to play around with:
http://kippenjungle.nl/kruisingKipFlexTree.html
Of course, this is all assuming that your birds are not "split" for anything and that there are no recessive genes for color or pattern at play.
