...has some exposure.? The bark is missing from one of the limbs on one of my younger trees. It is an area off of the main trunk around 6" long and bare to the wood. I do not know if the black pruning spray will help or if there is a material to wrap that area. I am afraid if we have a bad winter it could hurt the tree or be exposed to bugs or disease. I can remember years ago my former neighbor used to put some roofing cement on areas such as this on his trees but I only need a very small amount and want to put the right material on the tree. Anyone with some landscaping experience, I would surely like your advice. Thank you very much.

I think someone might have intentionally removed the bark. However, nothing will happen to it whether it is young or old. Trees have the ability to heal its wounds or cuts because they undergo secondary growth where new lateral cells are produced and the existing ones are sloughed out to form the bark. If you think another means can also help then go ahead with it.
I'm a botany student in a certain University.

try electricians or even duct tape .leave till next summer then remove if bark starts growing