First welcome to the site. Hope you find support and information helpful in your concours related endeavors
For cleaning it depends on what I suspect the problem is. A light detergent mixed with water on a cool surface takes care of bird droppings, dirt and dust. For wax that has gotten on the black - silicon and wax remover
After that I've used Lemon Pledge for years. It can create a situation where it can attract more blowing "stuff" and deepen the look of the black. Don't use any more than needed but it does remove the chalky look that the black can take on at times
Sure others have their favorite unfortunately often products we find that work don't stay around long without being changed or altered from their earlier form
