How to Measure Paint Thickness with a Coating Thickness Gauge

Paint thickness has a huge impact on performance, appearance and application. It can also be a key part of making sure that a coating meets industry standards, so it’s essential you test and measure and get to know exactly what you’re dealing with.

There are two states in which paint thickness is measured: wet film thickness and dry film thickness. As the names suggest, one is measured before the paint has dried and the other is the paint’s thickness after the solvent has evaporated and the paint has dried.

You can find coating thickness gauges suitable for measuring either wet film thickness, dry film thickness or both – and we’ve gathered everything you need to know about how a gauge works and how to go about taking a reading.

How a coating thickness gauge works

A coating thickness gauge is designed to measure how thick a coating is. Different types of gauges use different methods to determine the same result, ranging from simple handheld options to more advanced machines for complex measurements.

When it comes to measuring paint thickness, the most common type of gauge is a handheld digital device that uses a flash of light to raise the temperature of the coating for a very short amount of time. It then analyzes the time taken for the surface to cool again. This data is used to work out the thickness of the coating. The great thing about this style of paint thickness coating gauge is the fact that it is noninvasive, meaning it won’t be destructive for the products or samples you are testing.

Ultrasound thickness gauges

There are also coating thickness gauges that work using ultrasound. An ultrasonic gauge measures the amount of time taken for a sound wave to travel through the sample and back to the meter to work out the thickness. For an ultrasound reading, the gauge must be held perpendicular to the surface and at a defined distance.

Manual thickness gauges

Typically made from stainless steel, these are paint thickness gauges that are designed to measure wet film thickness. They can be pressed into the coating just after application and the user can read the appropriate measurement from the grooves cut into the device.

Mechanical thickness gauges

There are also mechanical gauges, which use a permanent magnet, a calibrated spring, and a graduated scale to measure the thickness of a coating. Like manual gauges, these are particularly useful in highly flammable atmospheres or underwater, where electrical devices may not be used safely.

Coating thickness gauge accuracy and calibration

The level of accuracy needed from your paint thickness coating gauge depends on the purpose of your test. Digital gauges can be measured to the micron, while manual gauges rely more significantly on the ability of the user. You can test the accuracy of your gauge by using a sample with a known thickness standard and then comparing the results of your tests  to the set standard.

Paint thickness gauges at Industrial Physics

We have several paint coating thickness gauges that have been designed to help you complete your QA process as quickly, easily and successfully as possible. These include:

Coatmaster Flex – TQC Sheen

This handheld gauge measures coating thickness immediately after application and is suitable for both wet and dry film thickness measurements. It is very easy to handle and can be used in all sorts of industrial environments. It is contactless and non-destructive and can measure coatings and paints on a huge number of surfaces, including metal, paper, rubber, ceramics, glass, plastic and wood.

Wet Film Thickness Gauge Stainless Steel – TQC Sheen

This practical thickness gauge is a hexagonal/octagonal precision measuring comb made of heavy stainless steel that will not be affected by acid or base elements. It is a wet film thickness gauge that is easy to use and suitable for resins, lacquers, varnishes and gels as well as paints. It is very handy in environments where an electronic gauge may not be suitable.

Surface Profile and Coating Thickness Gauge

This combination gauge can be used to measure both paint thickness and surface roughness. It has two different tips, to allow for the separate functions – a sharp tungsten carbide replaceable tip for surface profile measurement, a hardened round tip for coating thickness measurement, a glass plate for zero calibration. It is useful for measurements in the field and comes with a leather carry pouch.

Measuring paint thickness with Industrial Physics

With expertise in a wide range of industries, from flexible packaging to construction or automotive, our engineers are on hand to help you find the paint thickness testing solution that best suits your needs. Whether it’s a portable thickness gauge for on the go testing or a solution you plan to set up in your lab as a permanent step in your QA process. Interested in finding out more about our inks and coatings solutions? Look no further!