![]() I have seen many posts of such a gauge showing a value when i can clearly see it not set correctly to give such a reading, its a scientific gauge thats requires setting / zeroing being used by guys that come from valeting trade, sometimes it wont always go perfectly. Its just too much faffing around for many people who detail in one day to use such a machine I have spoken to a lot of detailers that have gave up using the ultrasound gauge as they want a point and squirt gauge one that works first time every time. With this is mind you have to use body shop and paint back ground knowledge and some common sense and plenty of time to take CORRECT reading around entire car. becomes one layer) or the paint system used was wet on wet again all the layers become one layer. The paint depth layers won’t show if a good key between coats (i.e. The paint depth layers the gauge it trying to separate can be as low as 5-20 microns ![]() Reason for this is car panels have underlying structures that can interfere with the readings. So the above means any carbon / plastic / fibre glass panel can ONLY be measured using ultrasound gauge which has to be interpreted each time a reading is taken or recorded. I can add to this as it would of been me and Dom talking about PDG on training days, and Dom famously asking "do you have to have a PDG to detail as a hobby?" and "do you need one of its your full time job"ġ) I trained over 100 pupils last year (2012) and many had a cheap PDG these all apart from one read 15% higher than an expensive accurate PDG that’s been calibrated.Ģ) These gauges only read total paint depth NOT individual layers and using magnetic and eddy current to obtain paint depthģ) These gauges only work on metal ferrous and non-ferrousĤ) The average paint depth of factory standard car is 100-120 microns total depth some as low as 70 mircons, or the thickness of a piece of high quality A4 paper or another way 0.07mm to 0.12mmĥ) Paint depth gauges that read in multiple layers are very expensiveĦ) Paint depth gauges that read multiple layers use ultrasound to obtain paint depthħ) The ultrasound gauges are best used on no metal surfaces for absolute accuracy but will work ok on metal surfacesĨ) Ultrasound depth gauges work better on large paint thicknesses with strong joining boundary’s between paint layersĩ) The ultrasound gauge has a scale called “gates” that have to be zoomed out to get complete picture of total amount then zoom in on many more readings in exact same area to obtain the “real” top layer paint depth Mikemike you are quoting a figure thats nearly 10 times thicker than whats on a car and calling it low figure. (admittably variables such as paint density, external temperature etc do have an impact on the speed of sound through the material It is a simple calculation of the speed of sound through the material (paint) and the time taken to travel through the paint to an interface. Surely PTGs are simply ultrasonic depth gauges and results should not need to be 'interpretted'. Only commenting because I was surprised by your comments about paint depth measurement based on my own experience within a different industry. ![]() So I wouldn't call the technology poor as nearly all cored turbine blades in aerospace technologies are checked using a similar methodology. TBH I have never used the PTGs used within this industry - but have done a fair amount of work completing Gage R&Rs on ultrasonic equipment used to measure the wall thickness of injected wax patterns to ceramic cores for turbine blades (some less than 0.6mm) and achieving 5% Study variance GRR results on some pretty tight tolerances. They have a use but are relied upon too much and over-hyped IMO compared to real world value and real world detailing (you could never use a PTG and be absolutely fine applying common sense).Surely PTGs are simply ultrasonic depth gauges and results should not need to be 'interpretted'. There are sonic paint thickness gauges for plastic panelled vehicles, but all PTG readings need to be interpreted and the devices are not infallible.
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