Abstract
Visual tests of nutrient inertness on 28 coating materials showed that only half were inherently inert to the attack of four selected species of fungi. One of the materials had fungistatic properties. The visual tests were useful for screening materials for more extensive testing
Tensile tests of coatings buried in soil showed that polyethylene and polyvinyl chloride were immune to deterioration, that a neoprene coating was infested with fungi and that a tar-imprognated cotton fabric was deteriorated to a marked extent in inoculated soil. By the use of “sterilized” soil, the influence of the physical and chemical properties of the soil on coatings can be separated in part from the action due to soil micro-organisms.
Insulation resistance measurements on coated pipes and cables buried in soil boxes gave sensitive indication of coating changes. Because of difficulty in maintaining a soil “sterile” it is not possible to separate the effects of moisture absorption and microbiological deterioration in lowering the insulation resistance. However, tests on various modifications of the soil showel that deterioration of neoprene coatings occurred in soils inoculated with aggressive fungi.
Coal tar enamel coatings resisted deterioration and out-performed asphalt mastic and petroleum wax coatings.
Polyethylene and polyvinyl chloride coatings resisted deterioration and showed better performance than neoprene coatings. 3.3.4
