A paint gauge is a device which is used to measure the depth of a coat of paint. These devices are most commonly seen in use in the automotive industry, where they are a useful tool for detailers and refinishers. They may also be used for quality control in a car manufacturing facility, for the purpose of confirming that a paint job meets the standards set by the manufacturer. A number of companies produce paint gauges, which can be found for sale through catalogs which supply automotive professionals.
The paint gauge provides a method of nondestructive testing to determine the depth of a paint job. This can be useful when checking for inconsistencies or areas of concern, and it is also very important when a vehicle is being prepared for extensive detailing. The concern is that it is possible to remove the clear coat which is applied to a paint job after the pigmented paint has been laid down, and if this coat is removed, it can eat into the underlying pigmented paint and necessitate a costly refinishing job to fix the mistake. With a paint gauge, people can avoid this problem.
Clear coats are applied in standardized thicknesses by manufacturer. With a paint gauge, someone can see how deep the paint is and determine how much of that depth is the clear coat, using this information when detailing the car to avoid breaking through the clear cut. It's important to be conscious of the layers of clear coating and UV protection for the underlying pigment, as it is possible to cause damage without realizing it until it is too late. Paint gauge measurements can be taken before and after detailing and at various steps along the way to confirm that the paint is still in good condition.
There are several ways in which a paint gauge can work. Mechanical gauges use a magnet, with the gauge determining paint thickness on the basis of how much force is needed to remove the magnet. These gauges only work with ferrous backings such as steel. Electrical paint gauges use electrical currents as measurements, while ultrasound gauges, which can be used on fiberglass and plastics, utilize ultrasound to measure the depth of the paint.
These devices are carefully calibrated, and should be kept in protective cases when they are not in use to avoid causing damage which could skew the readings on the gauge. It is also advisable to periodically recalibrate, either by following the recommendations of the manufacturer or by shipping the gauge out for recalibration. This will confirm that it is measuring accurately.