What Does Coverage Mean?
Coverage is defined as the rate at which a coating spreads on a material and is usually expressed in units of square feet per gallon or square meters per liter.
The coverage value helps a coating expert determine how much paint or coating is required and how much of the material's area will get covered with a given quantity of paint or coating. To determine the coverage or the rate of spread, the Pfund formula is used, which was developed by the paint instrument developer George Pfundis.
Corrosionpedia Explains Coverage
Coverage calculations can be performed for pigment coatings and clear coatings. When used for pigment coatings it is related to hiding power, and when used for clear coatings it refers to the area coated at a desired film thickness.
The rate of coverage or rate of spread is determined using the Pfund formula. According to the Pfund formula, the coverage obtained from one gallon of paint is dependent on its nonvolatile content, which means that one gallon occupies a volume of 231 cubic inches (0.1337 cubic feet). If no losses occur, then that gallon of paint contained 100% solids and the coverage obtained from one gallon of paint applied to a film thickness of 1 dry mil (one dry mil is equals to 0.001 inch or 0.0000833 feet) would be 1,605 square feet (0.1337 divided by 0.0000833).
The Pfund formula is:
Theoretical Coverage per Gallon = (Volume Solids) / (Dry Mils Required)