There are a few genes that are used to breed or turn E (extended black birchen pattern ) dominant to ER (birchen) . They dont have them all studied and documented. The one most common is called Melinizer gene and it darkens black and fills in black in certain area's trying to cover up the birchen color area's. It has more trouble turning the males solid black as there is more red or silver to cover up on the male . So in developing the a black family or variety the females turn black first. If you ever have a chance cross a black to a partridge or wheaten and you can see how it acts. Light blues more than likely have less Melinizer and other recessive black genes in them. They are not common but there are some varieties of blues described as nonmelinized blues. The chicks look like lavender chicks they are such a light gray or silver gray. The adults can be a challenge as they can tend to show black streaks in the blue. The lacing on a blue can be caused by the pencilling gene , but the optical color illusion on some blues , they look like they are laced. They are realy not in some cases, its just a light trick and the way it boun ces off the feather. The ones that dont have streaking in them look very much like a lavender. Some strains dont seem to turn white in the splash but are a light gray with lots of black splashed through the gray. There is a picture of some game bantams at Cackle Hatchery.com it show's the light colored chicks and the gray and black splashed adult, versus the white with black splash in the body feather. Its a matter of selection and to go light breed the lightest ones together and you can get a few that will be the light gray. The lacing is a matter of selection and or breed standard for showing. Extended black birchens tend to not have breast lacing, as extended black tries to block color on the front neck and chest. But both varieties of birchen can be selected to not have lacing, even in just a black birchen. Extended black birchen has a solid black bottom or a charcoal rear end and sometimes less penqiun markings. The toes will be a solid slate. ER birchen chicks will be very penquin marked with a cotton tail white rear, the toes will have some that have flesh color or lack of slate in the toes. This will turn slate as the chick ages and then the both have the same colored toes by maturity. The one lavender orpington I crossed the 3 chicks that hatched were Extended black and one was a very dark silver birchen pulletthen a male and another very dark male that showed no color in the hackle in the juvenile plumage. I was wondering if he might show some gold in the moult but lost him before he began to moult. Just trying to see if the lavender was a silver or split. He had to be at least split for silver to have a silver daughter. Most blue have come from black crosses at some point in time. Only a few black varieties in chicken are not birchen based, and all carry melinizer genes. The one common one is just called melinizer and given a symbol called Ml. Most blacks have two genes of melinizer. Hope this helps paint a genetic structure picture to help with the dark blue and the light blue. There are other darkening genes they dont have reasearch on. Just select for the color type you prefer. Its a long haul to color perfection and another to keep it maintained and not loose it. Color examples of a black cross are varieties of game the call brassey backs. Pictures of these are what happens when you cross a black to certain partridge colors and you can see what one gene of melinizer dose at trying to turn a bird black. They usually are black to a BBR or other partridge colored bird.
