This guide is based on the knowledge and experience of manufacturers@ users@ and researchers of room temperature vulcanizing (RTV) silicone rubber coatings that are used to improve the contamination performance of outdoor high-voltage (HV) insulators. This guide discusses various important aspects that are needed for satisfactory long-term performance of high-voltage insulator coatings (HVIC)??namely@ various possible application scenarios@ maintenance issues on coated insulators@ factors affecting long-term performance@ the question of aging@ laboratory accelerated tests@ and functional outdoor evaluation. However@ it must be mentioned that for any specific application@ judgment@ and experience are required to analyze and balance the many characteristics@ which are discussed to obtain satisfactory performance and reliability.