ASTM D2697

ASTM D2697 – Standard Test Method for Thermal Diffusivity by the Flash Method

Description:

Significance and Use

4.1 This test method is intended to provide a measure of the volume of dry coating obtainable from a given volume of liquid coating. This value is useful for comparing the coverage (square feet of surface covered at a specified dry film thickness per unit volume) obtainable with different coating products.

4.2 For various reasons the value obtained may not be equal to that predicted from simple additivity of the weights and volumes of the raw materials in a formulation. One reason is that the volume occupied by a solution of resin in solvent may be the same, greater, or less than the total volume of the separate ingredients: such contraction or expansion in resin solutions is governed by a number of factors, one of which is the extent and direction of spread between solubility parameters of the resin and solvent.

4.3 The spatial configuration of the pigment particles and the degree to which the spaces between the pigment particles are filled with the binder also affect the volume of a dry coating formulation. Above the critical pigment volume concentration, the apparent volume of the dry film is significantly greater than theoretical due to the increase in unfilled voids between pigment particles. The use of volume nonvolatile matter values in such instances should be carefully considered as the increased volume is largely due to air trapped in these voids.

Scope

1.1 This test method is believed to be applicable to the determination of the volume of nonvolatile matter of a variety of coatings. An interlaboratory study to establish the precision of this test method included a water-reducible exterior latex paint and three automotive coatings that included a solvent-reducible primer surfacer, water reducible primer surfacer, water reducible enamel topcoat, and acrylic dispersion lacquer topcoat. Earlier collaborative studies included a gloss enamel, a flat wall paint, a gloss house enamel, an industrial baking enamel, an interior latex paint, and an exterior latex paint. This method does not apply to radiation curable materials or pigmented coatings.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.