How to Use Wet Film Wheel Gauge Correctly to Measure Wet Film Thickness

Many tools come in special shapes and sizes. Tools in the field of industrial coatings are no exception. One of the unique tools used by paint professionals is the wet Film Thickness Gauge. To those unfamiliar with its proper use, an eccentric or "IC" gage looks like a clunky pizza knife. Wet Film Thickness Gauges are sometimes referred to as Inmont wet film gauges or "wet film wheels".

Wet film gauges are the standard for measuring wet film thickness. While standard wet film thickness gages are a quick and easy way to quantify wet coating thickness, wet film thickness gages are more versatile and accurate. For example, wet film gauges can measure wet film thickness on moving surfaces. IC gages can also easily measure paint or coating thickness on round or curved surfaces due to the round shape of the gage's measuring mechanism.

A wet film wheel gauge consists of two equal sized discs with a smaller disc in between, as shown in the example below. The smaller disc is mounted eccentrically to allow measurement as the three-disc wheel rolls over the wet coating. When rolling occurs, the internal eccentric disc is coated with wet paint. The measurement is recorded at the point where the center disk no longer touches the wet coating.

When using wet film gages, it is important to measure from the center disc that provides the greatest clearance to ensure that no wet paint or coating is accidentally shifted. Such errors can inadvertently lead to inaccurate thickness measurements and uneven coating distribution. As the discs roll through the coating, the paint will remain in contact with the center disc until the gap between the inner disc and the substrate is greater than the thickness of the film. The person making the measurement should roll the wet film wheel gage over the wet film at a slow, steady speed to obtain the most accurate results possible. Any quick movement or sudden application of the wet film gauge to wet paint or coatings can accidentally and inadvertently cause splatter or paint displacement.

The chemical gauge should also be thoroughly cleaned after each use. Any hope of accurate measurements can be achieved by leaving paint or coating residues from previous measurements on the gage. Using aggressive cleaning agents or abrasive materials can damage the gage disc, which will cause inaccurate measurements and render the gage unusable. Different quantities have different recommended cleaning methods, and it is important to consult the manufacturer's specifications for exactly how to clean any one particular gage.

While there are various ways to measure the thickness of a cured or dried paint or coating, measuring the thickness during the coating process is the better way to ensure the correct amount of paint is being used. Using a wet film wheel gauge will ensure that the proper thickness is applied across the substrate, resulting in an even coating that looks great and holds up well over time.