How to Properly Use an Interchemical Gage to Measure Wet Film Thickness 2

Many tools take on peculiar shapes and sizes.   Tools found in the industrial paint sector are no exception.  One of the unique tools utilized by paint professionals is the Interchemical Gage.  The interchemical, or “IC” Gage looks like a bulky pizza cutter to those that are unfamiliar with its proper usage.   Interchemical gages are also sometimes known as Inmont Wet Film Gages or “Wet Film Wheels.”

A Interchemical or IC gage

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The interchemical gage is the gold standard in measuring wet-film thickness.   While a standard wet-film thickness gage is a quick and easy way to quantify the thickness of a wet coating, the interchemical gage is more versatile and more accurate.  For example, the IC gage can measure wet film thickness on surfaces that are moving.   Due to the round shape of the gage’s measurement mechanism, the IC gage can also measure paint or coating thickness on round or curved surfaces with ease.

Interchemical gages consist of two identically sized discs with a smaller disc between them, as seen in the example below.  The smaller disc is mounted off-center to allow the measurement to take place as the three-disc wheel rolls through a wet coating.  The interior eccentric disc is coated with the wet paint as the rolling takes place.  A measurement is recorded at the point that that central disc no longer contacts the wet coating.

A representation of the interior eccentric disc of a interchemical gage

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When using an interchemical gage, it is important to begin the measurement with the central disc offering maximum clearance to ensure that no wet paint or coating is accidentally displaced.  Such a mistake could inadvertently lead to inaccurate thickness measurements and unevenly distributed coating.  As the disc rolls through the coating, the paint will remain in contact with the center disc until the clearance between the interior disc and the substrate is greater then the thickness of the film.   The person taking the measurement should roll the interchemical gage at a slow, steady rate through the wet film in order to get the most accurate results possible.  Any quick movements or sudden application of the IC gage to the wet paint or coating can accidentally and inadvertently lead to splashing or paint displacement.

The interchemical gage should also be thoroughly cleaned after each use.   Any hope of an accurate measurement can be undone by having paint or coating remnants left on the gage from a prior measurement.  The use of corrosive cleaning agents or abrasive materials can damage the gage’s discs, which will lead to inaccurate measurements, making the gage useless.  Different gages have different suggested cleaning methods and it is important to consult with the manufacturer’s specifications to understand exactly how to clean any one particular gage.

An IC or Interchemical wet film thickness gage

Image courtesy of UV Process

While there are a number of methods for measuring the thickness of a paint or coating once it has cured or dried, measuring thickness during the coating process is the best way to make sure that the correct amount of paint is being used.   Utilizing an interchemical gage ensures that the appropriate thickness is being applied across the entire substrate, leading to an even coating that looks great and holds up well over time.


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