American Manufacturing Company (AMC) requires that its employees wear uniforms and protective clothing while on the job, but the employees can't take the uniforms home, and must change at work. AMC provides a locker room for the employees to leave their street clothes and personal items while working. A sign on the back of locker room door states, "American Manufacturing is not responsible for the loss of any property in the locker room." Bob, an AMC employee, changes his clothes in the locker room before starting work and leaves his wallet and watch in a pocket of his jacket hanging in his closed and locked locker. When he returns after his shift, the wallet and watch are gone. Does Bob's leaving personal items in the locker room constitute a bailment? If so, what type of bailment? If not, what legal relationship is it? Does AMC's sign exculpate the company for Bob's loss? Why or why not?