DeFelsko manufactures hand-held, thickness gauges that are ideal for use by automotive paint detailers. They enable full service detailers to quantitatively measure and control the amount of clear coat removed when sanding and buffing automotive paints. Simple, affordable gage for total coating thickness measurement on metal panels. The PosiTest DFT series of gauges measure coatings up to 40 mils (1000 microns) making them ideal for non-destructive measurement of automotive paint thickness on a variety of metals. The PosiTest DFT Ferrous is ideal for measurements on steel panels, where as the PosiTest DFT Combo is available for measurement requirements on both steel and aluminum panels. With +3% accuracy and a 0.1 mil (2 micron) resolution, the PosiTest DFT provides the capability to measure the amount of paint removed while sanding and buffing. Approved by major Dealer Equipment Programs such as Toyota, GM, BMW, Nissan, Volvo, Mercedes-Benz, Hyundai and Volkswagen.

The ultimate Paint Thickness Gage helps you escalate your business to the next level. Show everyone how professional you really are. This lightweight and versatile unit automatically measures coatings on any metal even aluminum. DeFelsko manufactures hand-held, non-destructive coating thickness gauges that are ideal for use by automotive paint detailers. They enable full service detailers to quantitatively measure and control the amount of clear coat removed when sanding and buffing automotive paints. Manufactured in the USA to the highest quality standard. The Defelsko PosiTest  DFT Combo Electronic Paint Thickness Gauge measures the paint thickness on all metals, including steel and aluminum.

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 Q & A

What does a paint thickness gauge measure?

Magnetic and Eddy Current

Ultrasonic

Ultrasonic gauges use an ultrasonic transducer to emit a high frequency sound pulse. The pulse travels into the coating via a coupling gel and reflects from ANY surface that is different in density. Coating thickness readings are obtained by measuring the time taken for the ultrasonic signal to propagate from the probe to the coating/substrate interface and back. The travel time is divided by two and multiplied by the velocity of sound in the coating to obtain the thickness of the coating.

Ultrasonic models are available to either measure the total system thickness (like magnetic and eddy current gages) or the individual layer thicknesses in a multi-layer paint system. The affordable models are only intended for use over non-metal materials such as plastic.

What is clear coat?
The clear coat is polyethylene paint without color pigmentation. Thickness usually ranges between 1.5 to  2.0 mils (35“ 50 microns). It is the final original equipment manufacturers coating applied to a vehicle to protect the (base) color coat from a hostile environment while providing both depth and a durable, glossy appearance. It is easily scratched and, once compromised, requires re-painting, as the base color has no shine or brilliance. Also, the clear coat provides UVR protection for the colored paint layer.

Car manufacturers now specify that the paint thickness be measured before and after any wet sanding or buffing. Measurements should be taken regularly since it is virtually impossible to see how much paint is being removed during the buffing process. Using a paint thickness gauge gives a professional detailer credibility and also acts as an insurance against a break-though of a clear coat, which would entail a re-paint.

What should the paint thickness be?
 

Consistency is what is important. Measurements taken across a panel should show only small variations in thickness. Areas of reduced thickness may be a cause for concern. Areas of much greater thickness may indicate rework. If the instrument does not give a measurement, or reads “- - - -“ it means that the thickness is over the gage’s limit and could mean the presence of filler and a likely repair.

Are these instruments known by other names?
Although most industries call them coating thickness gauges, the automobile industry also uses names such as paint depth gauge, paint meter, refinishing gauge, dry film thickness gauge (DFT gages), paint thickness gauge (PTG), mil gauge, banana gauge, spot checker, or paint gauge. Spelling is either American (gauge) or British (gauge).

What do F and N stand for on the display?
Most instruments display the principle of operation used to take a measurement. “F� stands for ferrous metals (steel) and it means a magnetic principle was used to obtain the displayed measurement. “N� or “NF� or NFe� stands for non-ferrous metals (aluminum, copper, etc.) and it means an eddy current principle was used to obtain the displayed measurement.

Where else in the auto industry are these instruments used?
Detailers require a simple gauge with good measuring accuracy and resolution to monitor the decreasing thickness of clear coat with buffing. But the same or similar instruments are used by body shops, dealerships, painters, appraisers, inspectors, and professional car buyers at auctions.

Do I have to re-calibrate my meter often? The term “calibrate� is often miss-used. For a complete definition read this. Most people use the word to mean, “adjust to make accurate�. Quality meters automatically calibrate themselves regularly and usually require little input from the user except to RESET it if factory settings get modified, either deliberately or accidentally. All meters should be checked regularly for accuracy by measuring an uncoated piece of metal to ensure the gauge reads “0�, and/or by measuring the included plastic shims when placed over uncoated metal. Cheaper, lower cost instruments “drift� and therefore should be checked before use each day. Their probe tips wear and their electronic components have wide operating tolerances. When they read in error, a one-point or two-point calibration adjustment by the user is necessary as described in the user manual. You get what you pay for.

What is Detailing?

Detailing as it relates to paint thickness measurement is the systematic cleaning, rejuvenating and protecting of the exterior painted surfaces of a vehicle. The primary purpose for paint detailing is to retain the appearance of newer vehicles or to revitalize older neglected vehicles.

Cleaning is a preparatory step intended to remove dirt, dust, and other loose contaminants in order to allow full inspection of current paint conditions. Rejuvenation refers to the processes used to return a vehicle to its original showroom condition. The extent of rejuvenation is dependent on the customers expectations. Protection refers to the maintenance processes such as waxing that are used to keep the vehicle looking new for as long as possible after detailing.

Simple washing and waxing will not remove many types of surface paint damage; a rejuvenation step (polishing with an orbit or more effective high speed polisher) is added before the waxing step. When rejuvenation is required, detailers often polish the top clear coat layer of automotive paints to remove surface damage such as fine scratches, scuffs, swirl marks, oxidation, stains, paint overspray, tar, tree sap, acid rain or water spots. This polishing process is often referred to as finessing. Extensive paint problems may require the use of several sanding and buffing steps to bring the paint back closer to its original beauty.

Automotive manufacturers typically use one of two main types of paint systems in their vehicles. The most common used today is a clear coat system in which a thin layer of color is applied, followed by multiple layers of clear non-pigmented paint. Used less frequently today is a single-stage paint system that consists of the application of multiple layers of pigmented paint. Since most detailing chemicals are designed to work on both paint systems, the paint detailing process does not significantly change based upon the type of paint system.

Why measure?

To ensure consumer value and thus maintain profitability, there are two main considerations when justifying equipment and processes involved in the detailing process. Any added cost must result in improvements in either efficiency or effectiveness. While it could be argued that a detailers ability to take quick readings with a paint thickness gauge in order to determine the remaining paint thickness is an efficiency benefit, the primary benefit is the increase in effectiveness.

When the need to polish (sand and buff) has been identified it is important to evaluate the paint in surrounding areas. Most factory paint jobs seem to range from 4 – 7 mils (100 – 180 microns). Thinner readings indicate that the clear coat is almost entirely removed or in the case of single-stage systems that the primer is about to show through. As represented in the photo above, thicker readings are often an indication that repainting has occurred. When repainting is detected, the operator has a difficult task in evaluating the suitability (thickness) of the top layer of paint for buffing. No matter how careful the operator, buffing or polishing on thin coatings risk paint damage to the vehicle. When detailing thin coatings or unknown paint layer thickness, an alternative system such as hand polishing may be the only safe option.

After determining the paint system used on the vehicle and thus the expected paint thickness, it is important to determine the actual paint thickness. Even an experienced detailer finds it difficult to determine paint thickness, especially clear coat, through visual inspection. As thinner, more scratch resistant clear coats such as nano technology become more prevalent, it will become more critical to use high resolution electronic thickness gauge to determine how much paint thickness is being removed while finessing.

Because of the potential for removing the majority of the UV blockers, most auto manufacturers recommend that a maximum of 0.3 mils (8 microns) clear coat be removed as prevention from UV damage to underlying paint layers. In a worst-case scenario with a single stage paint process, buffing down to the primer may result in a costly trip to the paint booth.

Also consider that paint damage may not visually appear immediately. When too much topcoat is removed, premature failures such as fading or delamination may occur. Failures have the potential for lawsuits, unhappy customers and loss of reputation. Such risks can be alleviated by monitoring and minimizing the amount of topcoat removed, which is best done through quick and easy measurements with an electronic paint gauge.

Significant damage below the top painted surface may include deep scratches, etching, staining, and heavy oxidation. Just as simple washing and waxing will not remove some top layer paint damage, rejuvenation through sanding and buffing may not be adequate for removing deeper paint damage. It is therefore important to recognize the limitations before too much paint has been removed. 

Manufacturing Materials