POSITEST PG Paint Inspection Gauge

The PosiTest PG Paint Inspection Gauge is a precision instrument used to measure (destructive) the total coating thickness or individual layer thickness of coatings over any rigid substrate, including metal, wood, and plastic.
It can measure the individual layer thickness of a multi-layer coating system provided that the layers are of a different color. Measuring range: 0-1,250 µm. Successive, contiguous coats should be of contrasting colors to aid sharp discrimination of coating interfaces (ASTM D4138).‍
The PosiTest PG can be used to measure plating thickness on metal, ceramics, plastics, and more.‍

Per ASTM D4138, the measurement surface may be flat or moderately curved. Pipes as small as 25 mm in diameter may be measured in the axial direction.‍

The PosiTest PG uses a carbide cutting tip to cut a groove into the coating at a specified angle. The groove is then observed under an illuminated microscope, and coating thickness is determined using the scale markings on the reticle.
​Conform:

• ISO 2808/19399
• ASTM D4138
• JIS K 5600-1-7
• NF T30-123

The PosiTest PG has a durable anodized aluminum housing, the rotating cutting tip holder accommodates up to four cutting tips.
It has a powerful 50x microscope with precision optics and rotating scale in imperial and metric units, and the delivery includes all tools and accessories required for testing in accordance with national and international standards and also a calibration certificate with traceability to NIST.

How to measure:

• Select a location to perform the measurement that is flat and level.
• Make a mark approximately 50 mm (2”) long on the coating, using the included black marker, or another marker of a color contrasting to the surface.
• Pull out the selection dial and turn it to select a cutting tip based on the expected coating thickness, using the chart below. If the coating thickness is unknown, perform an initial measurement using the 2X cutting tip.
• Place the gauge on the surface, such that the cutting tip and guide wheel are flat and level on the surface. 
• Pull the gauge towards the operator, creating a perpendicular cut through the marked line. Apply just enough pressure to cut into the substrate. 
• Turn on the built-in light, and align the microscope over the intersection of the mark and groove cut. 2 Measurements in mils/inches should use the graduation marks above the center line. Measurements in microns/millimeters should use the graduation marks below the center line.
• Observe the cut through the eyepiece, focusing the microscope using the focusing wheel and rotating the eyepiece as necessary to properly align the reticle markings with the groove.
• Record the width of the cut, measuring from the edge of the substrate to the edge of the contrasting mark, by counting the number of graduations. If measuring a multilayer coating system, the width of each individual layer may be recorded
• Multiply the measured width of the cut by the conversion factor from the conversion chart (see manual) to determine the coating thickness.

The built-in light illuminates the measurement area to assist with optical inspection

The PosiTest PG features 4 cutting tip holders and a selection dial, with positions marked for the 1X, 2X, and 10X cutting tips. The fourth holder can be used for an optional cutting tip, or left empty for storing the guage. To rotate the cutting tip holder, pull out the selection dial and turn to the desired position. Release the selection dial, ensuring that the tip is locked into place.