What are rubber washers used for? Manufacturers use rubber washers as spacers, springs, locking devices, and wear pads. They also support threaded fasteners, particularly in the construction industry. In compressors, they absorb vibration and seal fluid as well as liquid connections. They absorb shocks and insulate electric motors. How do rubber washers work? Rubber washers are round, flat discs with a hole in the middle, which allows fastening components such as washer screws to pass through the center. Manufacturers use screws with rubber washers distribute the force of the screw head, which keeps the screw head from digging into surfaces and creating damage. Are rubber washers necessary? Wet areas commonly require the use of rubber washers. Washers are often made of metal, which can rust when exposed to moisture. They are also common on boats, swimming pools, pressure washers and other water-related equipment. Another benefit of rubber washers is that they are more flexible than metal washers. Does a rubber washer go inside or outside? You want the plastic washer on the outside for a watertight seal, and the nut on the box for mechanical strength and with a metal box, to bond the fitting to the box electrically.