Aqueous compositions useful as pretreatments prior to painting and to reduce the formation of rust in the uncoated condition consist essentially of water, an organo-functional silane, a compound of a Group IV-B element, and optionally a polyvinyl alcohol, stabilizing agents, wetting agents, thickeners, and biocides, and have an alkaline pH>7. The carrier head includes a backing assembly, a housing and a damping material. In addition, impurities contained in a metal catalyst can be prevented from being introduced into the nanowires, contributing to an improvement in the electrical and optical properties of the nanowires. The annular space is selected to be of a size such that the screen has is confined in a minimum space whereby hydrocarbon flow between the overlapping edges is closed off.