Solid content and volum solid content of finishing material
The finishing material is always consisting of the solid material and the thinner. The solid material is the paint, coating materials, pigment or the other finishing material which will remain on the surface when it is applied and dry. While the thinner is mixed of solvent that will evaporate entirely when the finishing material is dry. The function of thinner is to reduce the viscosity of the finishing material to make the material is easily applied and handled in the finishing process. The thinner is just a "vehicle" to deliver the finishing materials to its "destination" (the finish surfaces) The thinner will evaporate and disappear in the air during drying of the finishing materials.
According to the thinner, solvent and finishing materials there are some important terms to be understand, they are: viscosity, solid content and volume solid content. About the viscosity of finishing material we discussed in our article: viscosity of finishing material. Now in this article we want to discuss about solid content and volume solid content.
Solid content is the content of the finishing material in the paint or coating mixture. This solid material is the material that will stay and coat the surface and determine the outcome of the resulting finish. Some peoples may still think that the finishing materials with high viscosity will have high solid content. It is not really true. Solid content can not be measured with the viscosity, The solid content of finishing material depends on the composition of the materials in the paint and the solvent used to solve the paint. The relation of solid content and viscosity is varying from one material with the other. Every solvent is specific, some specific solvent is needed to solve the specific material. With proper solvent, the material with high solid content can have low viscosity, on the other hand the paint material that is thinned with improper solvent can have high viscosity although have low solid content.
To find the solid content of a paint we have to measure it. Solid content is obtained by measured the weight of the paint hat is left and stayed at the surface when all its thinner has evaporated divided by the weight of the paint with all his thinner.
It is how to check the solid content. Weight and record some amount of paint. Then heat the paint in the oven to let his thinner is evaporated. Then weigh the remaining dry paint. Solid content "usually expressed in percent" is the weight of the paint left when all of his thinner is evaporated divided by the weight of the mixture paint with his whole thinner in the mixture.
To illustrate we can see the following example: 100 grams paint that has 30% solid content means that the paint has 30 grams of a solid material that will left on the surface, while the rest about 70 grams of material is the paint thinner that will evaporate in the drying process. From this view it is very logical to be understood that the higher solid content is considered as better paint. The more solid material left on the surface means more surface area can be covered with the paint.
Volume Solid Content
Actually there is another parameter that better describe the quality of the paint instead of the solid content; it is the volume solid content. Volume of solid content is the size of the volume of a paint that will remain on the surface when his entirely thinner evaporates from the paint. Volume of solid content is measured by measuring the volume of paint in the mixture, and then paint is dried in an oven to evaporate his entire thinner and then measure the volume of paint left. The volume of solid content is the volume of paint that remains divided by the volume of paint with his entire thinner, usually expressed in percent. Volume solid content better describe the quality of paint because the volume of the finishing material that is left in the surface will determine the finishing thickness. The volume of finishing material left on the surface is also determining the surface area that can be covered by the finishing materials. The difference between the volume of material and weight of material is a function of the weight and type of material depending on the mixture of ingredient materials used and it is the secret formula from the paint manufacturer.