Cement is used to repair gouges in leather, particularly those that create a flap of leather that is still attached to the body of the boot. A very small amount is used to stick the leather back in place and allowed to dry prior to polishing. Leather cement dries pliable to allow the leather to flex without peeling away from the adhesive. A very common variety of leather cement is Barge Glue. It's often useful to have toothpicks available to apply the extremely small amount of adhesive needed to the proper spot.