I don't know about black cotton but some black fabrics do fade. Make sure you keep it out of direct sunlight and wash in cold water. I would resist the temptation to dry it in the dryer, but drip dry instead. I actually have had black clothing hanging in my closet that has faded on the hanger. Those items were not cotton, though. I couldn't get over it considering the closet is not exposed to direct sunlight. I have a habit of not closing the closet door so the light coming through the window in the bathroom was just enough exposure to fade those clothes. We're talking about a north-facing window! i had a wallhanging that was never exposed to direct sunlight but in a very bright northern facing room and on a wall above a lamp. All of the navy blue faded over time. It won't stop me from using navy and black but I will definitely take extra precautions to avoid the problem in the future. If you give a gift to someone with those colors make sure you give them instructions on how to take care of the item.