The barring gene does diminish pigments in the skin and eyes. So remember that if you are planning on making a bird or variety that is supposed to have certain color legs or eyes. Usually you will end up with white legs and yellow eyes.
There are other factors involved in what you can see, such as a white chicken may be barred but you cannot see the barring, but consider B as barred and b as not barred.
A hen only carries one of these genes. It is a sex linked gene, so she is either "B" barred or "b" not barred. She gives this gene to her sons but not her daughters. That is how you get black sex links.
A rooster can be "bb" not barred, or either "Bb" or BB", both of which will show as barred (depending on what else is there, like the solid white). He will give one of his genes to all his offspring, either male of female. If he is Bb, he may give either gene to either offspring, so the offspring may or may not be barred.
If he has BB, he will be lighter in color than rooster that is Bb or a hen that just has a single B. That is why, if you have chicks that are pure for barring and that barring can be seen (again thinking of that pure white where barring is hidden. There can be other factors), the lighter chicks are probably roosters and the darker chicks are probably pullets. If you have a mixed bin of pure Barred Rock chicks and Black Sex Links both present, the lighter chicks are probably BR males, but the darker chicks could be either BR females or BSL males. That can make it challenging at TSC chick days when you are picking chicks out of a bin.
Chris and Sonoran both know more about this than I do. I'm pretty comfortable with what I said, but if I got anything wrong they should correct me.
OK, When talking about barring as in Barred Rocks, American Dominique, Cuckoo Marans etc.
The below information is from the book Exhibition Poultry Keeping by David Scrivener
Barring Gene: B
This is a Sex-link gene that stops and starts pigment production as in feather growth to give the well-known barring pattern as seen on Barred Wyandottes and Scots Greys. The extremely narrow and sharp barring seen on the Barred Plymouth Rocks is achieved by the presence of the gene ('K') for very slow feathering growth,which allows for a lot of on/off sequences in the time it takes for a feather to grow. The same barring gene ('B') when on a rapid feathering breed gives wide, coarse, fuzzy "Cuckoo Barring" as seen on Cuckoo Marans, Cuckoo Pekins (Cochins) and others. The barring gene also interacts with the gene on the E locus, all of the above examples being based on the E plus melantoics. Thus all these barring and cuckoo breeds would be self-black if they did not have the barring gene. This gene has greater pigment-restricting effect on black pigment than it does on red or gold pigment. When the barring gene is applied to the Wild Type pattern, the Crele variety is produced; and the barring on Columbian pattern combination is seen on Rhodebars, one of the autosexing breeds.
It is to be hoped that most, preferably all readers of this book are already familiar with the principles of sex-linkage. They should be aware that the barring gene is not completely dominant to non-barring, which is why both dark- and light-barred males are seen, but only dark-barred females.
In most breeds with a Crele variety, Crele OEG for example, the richer colored males that have only one barring gene are exhibited, but in the autosexing breeds only light males carry two barring gene should be exhibited and (in normal circumstances) bred from. The phrase "in normal circumstances" is used here becouse some inbred strains of autosexing breeds are sometimes revived by crossing with the other related breed, for example Brown Leghorn for Gold Legbars. Dark Crele males may be used as part of the process.
Autosomal barring is not recessive and is not a single gene. Both genes necessary (Db and Pg) are dominant.
But their dominance is better in 2 doses each, as is the case for most chicken (color) genes.