Most car manufacturers will only allow ~ 25% of the clear-coat thickness to be removed without voiding the paint warranty and long-term durability problems becoming an issue. The clear coat provides gloss plus physical protection from the elements, including ultraviolet (UV) radiation, which is in the upper level of a cured clear coat. ![]() The following are the maximum allowable clear coat reductions the major USA car manufacturers will allow before the paint warranty becomes void Chrysler- 0.5 Mil (12µ) Ford – 0.3 Mil (7.5 µ) GM – 0.5 Mil (12µ) (Source - Automotive International) As a point of reference a sheet of copy paper is 89 µ. Modern clear coat paint finishes are so good today that they lull people into thinking that vehicle paint has protection and shine when in reality there is not really much there, other than the clear coat that has a thickness of ~25.4 µ. There are models that measure only ferrite containing alloys and others that measures alloys of all metals (aluminium panels for example), and the top model that measures any type of surface They usually come with testing ‘metal shims’ that have a thickness marked on them so you can check the readings obtained and recalibrate if necessary The PTG unit’s calibration must be checked before use if you’re going to rely on the information. + / - 2µ (micron) based on measuring the magnetic force and determining how thick of a non-conductive coating is covering the substrate, or sonic resonance (ultrasound) instead of magnetic forces, thus its ability to measure on non-conductive substrates. Using this as a guide to how much clear coat you can remove without compromising the paint system is much better than polishing ‘blind ‘its value is in diagnosis as opposed to guesswork Paint polishing entails the removal of scratches from the clear coat, but the PTG shows the total paint thickness, so we need to know the average clear coat thickness.Īs you can see, a PTG will only give you an approximation of the clear coat thickness you need to take an educated guess as to how much each layer consists of. Most paint thickness gauges (PTG) work by sensing the distance between the sensor and the metal base material, which means it`s measuring the (primer, base, colour, and clear coat) the total paint thickness. A mil reading will not change that rapidly during the process.īefore using a paint thickness gauge (PTG) you must understand the units of measurement used the relevance of the numbers shown and what you are actually measuring. Micron (µ) readings will constantly change as I sand keeping me constantly informed of how much is being removed, and will need to be accurate. If you are going to get into heavy correction such as wet sanding, you will be quickly removing clear coat, and will need to keep track of how much is being removed, and will need to be accurate. ![]() One micron is roughly 1/80th of the thickness of a human hair (hair thickness depends on hair colour/ethnic origin etc) I always want to know where I am at all times in terms of paint removal. I use the micron measurement because it`s so much smaller. A micron (µ) is much smaller than a mil there are 25.4 millimetres in an inch and a micron is 1/1000 of a millimetre. The alternative measurement is called a (µ) micron, which is a metric unit that equals one millionth of a meter, or 1/1000 of a millimetre. The clear coat will generally measure between 1.5 - 2.5 mils ![]() A typical factory paint job will measure between 4.0 and 6.0 mils. The first and more common and standard measurement are called mil. The travel time is divided by two and multiplied by the velocity of sound in the coating to obtain the thickness of the coating.Film thickness can be measured using two units of measurement. Coating thickness readings are obtained by measuring the time taken for the ultrasonic signal to propagate from the probe tip to the coating/substrate interface and back. How it Works: The PosiTector 200 B probe emits a high frequency sound pulse that travels into the coating via a coupling gel and reflects from ANY surface that is different in density. The PosiTector 200 B3 (Advanced model) is capable of measuring both TOTAL coating thickness AND up to 3 individual layer thickness in a multi-layer systems.The PosiTector 200 B1 (Standard model) is the economical and most common solution for measuring the TOTAL coating thickness.It is ready to measure out-of-box with no calibration adjustment required for most applications. The PosiTector 200 B ultrasonic coating thickness gage is ideal for measuring paint thickness on automotive plastic bumpers, fascias and other exterior and interior parts.
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