ASTM D2697:03(R2021) pdf free download – Standard Test Method for Volume Nonvolatile Matter in Clear or Pigmented Coatings.
4. Significance and Usc
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.
43 The spatial configuration of the pigment particles and the degree to which the spaces between the pigment parlicles are tilled 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.
5. Apparatus
5.1 Analviical Baltu,ce.
5.2 Sie’el Disk, preferably stainless steel. 60 nim (2% in.) in diameter and 22 gage (0.65 mm) in thickness with a small hole near the cireumference. A fine wire, such as Chromel A. 28 gage (0.32 mm), is attached through the hole and made the appropriate length for subsequent suspension of the disk in a liquid. The wire should have a small loop on the upper end so the disk and wire can be hung by this loop on the balance.
Nm- 4—Instead of steel disks. some analysts use alumInum tubes. In the round-robin results. essentially no difference was found in the precision obtained by both methods. Source and dimensions ot these tubes are described in the annex.
5.3 Counterweight. to he placed on the balance stirrup after hanger bow and pan are removed.
5.4 Beaker. I -L—For easier manipulation during the weighing of disk in liquid it is advisable to cut the beaker to a height of 115 mm (4½ in.).
5.5 Support for holding the beaker under the balance stirrup without jamming the pan damper in the floor of the balance. A cork or neoprene ring is suitable when a single-pan balance is used.