Abstract
Principal characteristics of cold applied coal tar coatings are considered with respect to applications. After reviewing the prerequisites of surface preparations, criteria for selection with respect to the exposure are considered. Five classes of coatings produced by one or more manufacturers are itemized and their general characteristics outlined. Care in selection of primer is emphasized and types of acceptable primers to be used under coal tar coatings mentioned.
After reviewing briefly the problem of water vapor permeability the author discusses the theory of transmission and gives definitions of transmission rate, permeance and permeability. Methods whereby these characteristics may be evaluated with respect to a specific coating are given. Results of an investigation of vapor transmission rates for three classes and one system of coatings are tabulated. Permeance of commonly used building materials is tabulated.
Recommended coal tar systems for numerous exposures of piling, pipe, and other metal structures are given. 5.4.5
