Film Build

Definition - What does Film Build mean?

Film build is the thickness produced in a paint application. The conversion of a material in a container into an adherent and durable coating is the process of film build and is generally comprised of three main steps:

  • Application
  • Fixation
  • Cure

Film build is particularly important to exterior paint because the durability of film is usually proportional to the film thickness.

Corrosionpedia explains Film Build

Film build is the thickness produced in a paint application. Paints are applied to surfaces by many methods, but in all cases this produces a wet film. The thickness of the wet film can be measured, before the solvent evaporates, using a comb-gauge. As the solvent evaporates, film formation occurs, leaving the binder and pigments on the surface as a dry film. The thickness of the dry film can be measured with an electromagnetic induction gauge.

The relationship between the applied wet film thickness and the final dry film thicknesses (DFT) is determined by the percentage volume solids of the paint:

    DFT = wet film thickness × the % vol. solids

In general, the corrosion protection afforded by a paint film is directly proportional to its dry film thickness.

Resin is the primary ingredient of an organic coating, the part of the coating that forms a film when dry. The resin is mixed with other ingredients to create an engineered product of applications. As the coating is applied, it flows and stabilizes into a relatively uniform film. This stage is referred to as fixation. After the coating has stabilized, it is cured by time, temperature or some other means.

Film thickness measurements should not be made close to the edge of a steel surface, as the magnetic properties of the steel influence the reading, causing distorted results. Always measure a clean surface, never an oily or dirty one.

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