This SAE Aerospace Recommended Practice (ARP) describes methods of masking and cleaning commercial aircraft, epoxy and polyester matrix, composite parts prior to their entry into the composites shop, masking and cleaning of on-wing repair areas in preparation for carrying out repairs and wipe cleaning during repair and prior to bonding. It this document is used for the masking or cleaning of materials other than epoxy and polyester matrix thermosetting composite materials, the fitness for this purpose must be determined by the user. The methods of masking and cleaning described in this document have specific limited application and are not interchangeable. The methods shall only be used when specified in an approved repair procedure or with the agreement of the Original Equipment Manufacturer (OEM) or regulatory authority. The intention of the descriptions in this document is to describe materials and equipment generically in sufficient detail to allow a suitable commercial product to be purchased. It is not intended that the information provided be biased to any particular manufacturer and no commercial product is recommended in preference to any other. The purpose of this ARP is to provide a set of standard methods for masking and cleaning of thermosetting composite materials that may be referenced in repair documents produced by airlines or airframe and engine manufacturers. It is intended that this ARP be one of a number of ARPs that will cover other aspects of the techniques required to perform composite repairs. These ARPs will provide a suite of available repair techniques that are acceptable for use throughout the commercial aircraft industry.