Volume solid is the volume of paint after it has dried. Paint contains solvent, resin, pigments and additives. After applying the paint, the solid portion will be left on the substrate. Volume solid is the term which indicates the proportion of the solid contacting the paint on a volume basis. For example, if paint is applied in a wet film at a 100 µm thickness, and the volume solid of paint is 50%, then the dry film thickness will be 50 µm as 50% of the wet paint has evaporated. Suppose the volume solid is 100%, and the wet film thickness is also 100 µm. Then after complete drying of the paint, the DFT will be 100 µm because no solvent will be evaporated.
This is an important concept when using paint industrially to calculate the cost of painting. It can be said that it is the real volume of paint.
Here is the formula by which one can calculate the volume solid of paint,
(Total sum by volume of each solid ingredient in paint x 100%)/ Total sum by volume of each ingredient in paintIn earlier days, the volume solid was measured by a disc method but now a sophisticated instrument is also available which takes only a drop of paint to check the volume solid.