A forklift operator was moving a plastic returnable (3ftX3ftX2in) on the forks of a forklift. The employee was attempting to place the returnable in a cart that has the same dimensions as the returnable base. While attempting to set the returnable on the cart he had difficulty aligning the returnable with the cart. The cart has casters so it moves around. The employee decided he would go around to the side of the returnable in an attempt to align it with the cart. While backing up he placed his right hand on the outside of the roll bar of the forklift. While doing so he twisted his body in order to look over his right shoulder. As he was backing up, he hit a center column to the building to which a steel sign was attached and protruding. That protruding steel sign severed the middle and ring fingers of his right hand. The signs had been placed on the columns throughout the workplace as a warning for employees to stop before crossing the drive aisle.