Paint and other liquid coatings are applied in the manufacture and finishing of a vast range of goods and products including metal sheet and coil, timber flooring, automobiles, aeroplanes, fencing, glass, packaging and the like. In the area of metal sheet and coil, the substrate is typically galvanized steel, aluminium, stainless steel, or zinc alloy coated steels including aluminium-zinc and zinc-magnesium coated steels.
Methods are available to measure the paint weight solids to ensure the quality of paint used in coating processes. However, the measurement of paint weight solids does not provide a precise measure of the cover that can be expected for a given volume of paint at a specified paint thickness. This is because two different coatings with the same value for paint weight solids are likely to have different average densities. The constituents of coatings include solvents, diluents, extenders, pigments, fillers, resins, flattening agents and so on, each component having specific gravity values. For this reasons the two coatings with the same value for paint weight solids are likely to have different values for paint volume solids. A value for paint weight solids is needed to estimate the cover that can be expected from the particular paint. Methods are also known for the measurement of paint volume solids. However, such methods and associated apparatus are relatively slow, inefficient, and inaccurate.
Apparatus and mathematical models are available to estimate the wet paint thickness that is applied to an industrial paint sample apparatus such as a roll coater, or to a moving metal sheet coil substrate (for example, during coil paint sample), or to substrates such as pre-made flooring and a myriad of other substrates. Without knowledge of the paint volume solids of the paint being used the thickness of the paint sample when dry cannot be accurately predicted.
The paint volume solids content property of liquid paints is the percentage of the wet paint that forms a solid paint sample; the balance being solvent(s) and/or diluents that evaporate during the drying phase of the paint sample process. For example, paint with volume solids of 50% will essentially cover twice as much area as a paint sample with 25% volume solids for the same paint sample thickness. The property of paint volume solids has particular application in an industry involving large scale application of paint. Improved methods for measuring paint volume solids would benefit coil coating, paint manufacturing, printing and automotive finishing, and other finishing or paint sample processes.
References to paint in the patent specification should be extended, in meaning, to cover or include inks, liquid suspensions, solutions, or inert, and reactive chemical coatings.