Paint Testing
Introduction
Paint is used as a description of a wide variety of pigmented wet applied coverings. The essential properties are a pigment in a liquid, which serves as a transport medium and a binder when hardened.
The properties of interest when tested after application are normally, film and layer thicknesses and chemical compositions. Where old paint is to be removed for refurbishment the levels of toxic components, such as cadmium or leads should be determined.
Thicknesses are determined by removing a small sample of the paint, as a flake, preferably including the substrate. This sample is mounted in resin and sectioned to provide a sharp polished cross section. A calibrated microscope is then used to measure the layers.
Chemical composition can be determined by a combination of scanning electron microscopy energy dispersive spectroscopy, infrared spectroscopy and pyrolysis gas liquid chromatography - mass spectrometry.
References
TBS6150: 1991 Code of Practice for painting of buildings
BS3900 Methods of test for paints
B4:1986 Determination of total lead in paints and similar materials
B6:1986 Determination of 'soluble' lead content
B9:1986 Determination of 'soluble' cadmium content
B12:1986 Determination of 'soluble' mercury content
C5:1997 Determination of film thickness
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