Most boxes have black shafted barbells in them- but did you know that not all black finishes are created equal?
This is a common and inexpensive steel finish. The raw steel is immersed in a bath where a black colored oxidation occurs on the surface of the steel. Black oxide is a good finish for bars- it provides an excellent feel in the hands, takes chalk well, and looks great when new or well cared for. A significant downside to black oxide finishes is that the will corrode and allow rust in many environments. The more humid your garage or gym, the faster the bar will rust if you don't oil it regularly.
"Black Zinc" finish is more expensive than black oxide, but it carries all the benefits of black oxide plus much greater rust resistance. A black zinc finish is created when steel is first immersed in a bath and given a bright zine finish, and then immersed in a second bath for a black oxide finish on top of the zinc finish.
What about Bright Zinc?
A bright zinc finish is created when steel is immersed in a bath and zinc is plated onto the steel. This is a high quality finish with strong corrosion resistance, but some people feel that oxide coatings (including black zinc) have a better feel for weightlifting. And, many people prefer a black bar!