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PosiTector 200 - Measuring Coating Thickness on Wood, Plastic, Concrete and More

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Measuring Coating Thickness on Wood, Plastic, Concrete and more with the PosiTector 200 from DeFelsko- the Measure of Quality

For decades, measuring coating thickness on metals has been possible due to their magnetic and electrical properties. But measuring coating thickness on non-metals was limited to destructive methods.

Everything changed in the 1990’s, when DeFelsko introduced the PosiTector 100. For the first time, it was possible to measure coating thickness over a range of substrates using a novel method- ultrasound. Similar in principle to sonar and radar, DeFelsko ‘broke the sound barrier’, by making ultrasonic measurements possible on coatings as little as a few microns thick.

Since then, DeFelsko has continued to perfect its ultrasonic technology. The PosiTector 200 is the result of five generations of product innovation, and for many applications it remains the only economical non-destructive coating thickness measurement option.  The proven technology has been validated by organizations all over the world, and its use is documented in standards such as ASTM D6132 and ISO 2808.

PosiTector 200 probes connect to the award-winning PosiTector platform, allowing a single gage body to accept environmental, coating thickness, surface profile, dew point, hardness, wall thickness, and soluble salt probes

The core of the PosiTector platform is the gage body. There are two:

The Standard gage body includes a bright color display, storage of up to two hundred fifty readings, and has a USB port for connection to a Mac or PC. When connected to a PosiTector 200 probe, it can measure the total thickness of a coating system.

The Advanced gage body includes additional features such as WiFi and Bluetooth, and stores one hundred thousand readings in up to one thousand batches. When connected to a PosiTector 200 probe, the thickness of up to three individual coating layers can be displayed. A powerful graphics mode is ideal for visualizing the coating system and evaluating new applications.

Three PosiTector 200 probes are available depending upon the desired application. The B probe is ideal for measuring polymer coatings on substrates such as wood and plastic.  The C probe measures polymer coatings on concrete and fiberglass. The D probe is designed to measure thick, soft coatings such as polyurea. All PosiTector 200 probes arrive calibrated and ready to measure, and include a long-form certificate of calibration traceable to a national laboratory.

Taking measurements with the PosiTector 200 is easy. First, it is recommended to zero the probe- simply clean the probe tip, hold it in the air, and select ‘Zero’ from the calibration menu. Unlike magnetic or eddy current gages, there is no need to measure on the uncoated substrate.  

To help the ultrasonic signal penetrate the coating, a liquid couplant is applied to the measurement area. The included gel is ideal for rough coatings and for vertical surfaces; alternatively, a drop of water is often sufficient for smooth coatings on horizontal surfaces. Only a small amount is necessary.

To measure, simply place the probe on the coating and press down. The instrument sends a sonic pulse into the coating and listens for a reflection from the coating-substrate interface, displaying the thickness measurement on the display.

International organizations such as ISO, ASTM and SSPC recommend calculating the average of several readings. This is easy with the PosiTector 200: simply turn on memory to display a running average alongside the minimum and maximum values.

When connected to an Advanced gage body, PosiTector 200 probes can also measure the thickness of up to three individual coating layers in a multi-layer system.

PosiTector 200 Advanced models also feature a graphics mode. After each measurement, a chart is displayed showing the reflected ultrasonic pulses. The left and right sides of the chart represent the low and high ends of the measurement range, respectively. The strength of each reflection is shown by the size of the peak.  

Graphics mode is ideal for measuring coating systems where the number of layers is unknown- a distinct, repeatable peak indicates a reliable measurement. In this example, a clear reflection is visible from between the layers, and off the substrate. Selecting three layers from the gage menu quickly displays these individual thicknesses. The cursor can be used to measure the depth of smaller reflections, and to measure the thickness of additional layers.

Measuring coating thickness with the PosiTector 200 on most coating/substrate combinations is usually as simple as powering on the instrument and taking a measurement. But the PosiTector 200 has some unique features to facilitate measurement on challenging applications, such as rough or textured coatings.

For more information, view our Coating Thickness Measurement on Rough Surfaces video.  

For over 25 years, DeFelsko has been the leader in ultrasonic coating thickness measurement, manufacturing simple, durable, and accurate gages. Backed by DeFelsko’s renowned quality, customer service and exceptional two-year warranty, the PosiTector 200 is the ideal choice for measuring coating thickness on non-metals.