You should not get any deterioration of black color. If you cross a black bird with a blue bird you are actually cross a black bird with a black bird. In order to get a completely black bird or completely blue bird the bird should be, E/E, homozygous for extended black and should carry black intensifiers. Both the birds should have the same intensifiers and extended black genes. If you cross them, they should produce birds that have the same genes.
Birds that are darker will carry more black intensifiers while lighter birds would carry less intensifiers. The only way the black color or blue color would lighten would be because you have breed out the intensifiers.
Lacing is caused by the Pg or pattern gene and Ml or Melanotic (a black intensifier). If both birds are pure, have two pattern genes and two melanotic genes , then they should pass on both genes to their offspring. There shouldn\'t be any deterioration.
I have black birds that do show lacing. The lacing is a darker black and reflects light differently than the rest of the feather. You will have to look at the feather at an angle and you will see the lacing. They came form a cross I made between a black jersey giant and a blue brown easter egger. I have one female from the cross that is a very good example of blue. The feathers are blue and each feather is laced with black. Her head and neck are darker blue because of the melanotic she carries.
Rooster
