PREDICT THE THICKNESS OF PAINT

November 21, 2014

It is easy to predict the thickness of paint after it dries. All that is required is that you know the “percentage of volume-solids” of the paint and that you have a “wet-film-thickness gauge”. The paint’s volume-solids (not to be confused with “weight-solids”) is listed on the Product Data Sheet, which can be found on the paint manufacturer’s website. A “wet-film-thickness” (WFT) can be purchased at professional paint stores or online, or obtained Free from Carbit.

In previous articles I discussed “paint volume solids”, which I described as “what’s left after the paint dries”. In that article I explained that as paint dries it shrinks in direct proportion to its volume solids. For example, a paint with 50% volume solids will lose one-half of its volume as it dries. If it is 4 mils when wet it will be 2 mils thick (4 x 50%) when dry.  Paint Volume Solids Fortunately, the

Wet-Film-Thickness (WFT) of a coating can be easily measured with a Wet-Film-Thickness Gauge.

To use a WFT Gauge you depress the graduated edge of the gauge into the layer of wet paint immediately after it has been applied. Withdraw vertically and note deepest tooth having paint on it and the next higher tooth that is not coated with paint. The true wet film thickness lies between these two readings.

In the U.S. the thickness of paint is expressed in mils (one mil equals 1/1000 of inch). The rest of the world expresses coating thickness in microns (1 micron = 1 millionth of a meter and 25.4 microns = .001” inch or 1 mil). The table below compares the thickness of common materials in mils and microns.

Being able to predict the thickness of paint has many practical benefits:

• It ensures that you are applying the correct amount of paint to achieve the performance properties of the coating.
• Coating thickness correlates to dry-time, recoat time and appearance.
• And, the ability to predict the thickness of paint helps you control cost.

For more information or help to predict the thickness of paint that you are applying complete our “get-in-touch” form below or call us at 312-280-2300. Bob Lyons – Carbit Paint Company, LLC – November 2004