ESDU 86040 gives guidance on the selection of treatments that include traditional techniques, such as carburising and electroplating, and more recently developed methods, such as the chemical or physical vapour deposition processes and processes involving lasers or electron beams to alloy or remelt the surface layers. Selection of an appropriate treatment is aided by an appreciation of wear mechanisms and by an understanding of the mechanical requirements of the contacting surfaces. Accordingly, guidance is provided on those two topics. A selection procedure is developed supported by tabular information on the properties of the treated surfaces including such considerations as hardness, treatment temperature, depth of treatment and rate of application, corrosion resistance, cost, and so on. A specification sheet is given for each type of treatment that summarises salient features including surface preparation and final finish, damage risk, partial treatment of component, and size limitations.