Why is it Important to Measure Wet Film Thickness?

A wet film is the coating on a surface which has not yet dried or cured and can be one of many things i.e. icing, chocolate, oil, varnish etc. But, in our field, it's most commonly paint.  Firstly, let's look at the two components that go into making paint:

Volatile Component: This is the part of the paint which evaporates during the curing process. Known as the “carrier”, “solvent”, “vehicle” or “liquid”, the volatile component provides the correct consistency to enable the pigment and binder to be applied to a surface.

Non-Volatile Component: This is the paint that remains after the curing process. Non-volatile components can be split into two;

1. Pigments – fine particles that provide the “colour” and typically include titanium dioxide (TiO2) for white and other colouring pigments as required.

2. Binder - the main body of the paint which holds it together and carries the pigment.

Paint can be applied to a surface using several methods such as a brush, a roller, spray and dipping or immersion. Therefore, the volatile and non-volatile components vary in viscosity.

Why Measure Wet Film Thickness?

The ability to measure the wet film thickness is important for financial, logistical and quality reasons.

Calculating Dry Film Thickness

The predicted dry film thickness can be calculated from the wet film thickness using a formula.

How to Measure Wet Film Thickness

Wet film thickness can be measured using a wet film comb, a wet film wheel or a Pfund gauge.