Paint Film Thickness

[TOGWT]

Paint Film Thickness:
Most modern vehicle paint film systems (paint build) comprise a primer coat of 2 Mil, a colour coat of 1-2 Mil, and clear coat of 2-3 Mil, an unprotected paint surface will lose approximately 0.004 Mil (0.00004-inch) to environmental exposure in a twelve month period (dependant upon geographic location)

As a point of reference a sheet of copy paper is 3.5Mil (0.0035") removing more that 10% or 0.3 Mil (0.0003") of clear coat will cause premature paint film failure

Mils-Coating thickness measurement - used in the paint industry to measure thickness (in the case of a paint film surface this should be `thinness') a Mil is 1 / 1,000th – inch (0.001 inches or 0.0254mm)
Micron- 1/1,000 of a mm or 1/25,000 inch or 0.00004 inches 25.4 Microns = 0.001– inch (1-Mil)

The clear coat provides protection from a hostile environment and an excellent brilliance, but is easily scratched; once it is compromised repairs involve re-painting, as the base colour has no brilliance, shine or depth, start with the least abrasive product to accomplish desired results, and only if necessary move up to the next grade of abrasive.

Q: What is the "right" paint thickness for a vehicle?
A: There is no "right" paint thickness for any vehicle. Automobile manufacturers paint thousands of vehicles each day with a wide variety of paint formulations; their specification has a range of thicknesses. For some models this can be as low as 3 Mil and, in the case of the rocker panels of Sports Utility Vehicles (SUVs), as high as 17 Mils.

Q: If there is no "right thickness", what am I looking for?
A: Paint thickness consistency; for example, when you are reading between 3.5 and 5.0 Mils and a reading shows a sudden reduction in thickness, you know there is a cause for concern in that particular area of the bodywork.

Paint Thickness Gauge (PTG) - most paint thickness gauges work by sensing the distance between the sensor and the metal base material. That’s total distance, which would be the thickness of all layers (primer, base, colour, and clear coats) and any repainted material, etc. You have to take an educated guess as to how much each layer consists of.

An electronic paint thickness gauge can be an invaluable tool, before buffing it’s always a good idea to check the paint film thickness to see how much of the paint film thickness available, check is periodically during the process and on completion to see how much was removed. Take measurements with a paint and coating thickness gauge and mark them on a template so that you have a reading of before / after polishing. Take readings on each panel left – right every 2- 4 inches, then drop down 2-inches and repeat. – Paint Thickness Template - Image of Detailing Template - Photobucket - Video and Image Hosting

Using a paint thickness gauge gives a professional detailer credibility and also acts as an insurance against ‘break-though’ of a clear coat, which would entail a re-paint and I suspect a very irate customer. Original paint has a better resale value than a re-painted vehicle, plus they will lose the use of their vehicle for some days. The ideal setup would be a DFT Combo for the metals and a PosiTector 200 B/Adv for the composites.

If you use a car outline template and mark the paint thickness, you can advise the customer of any potential problems and you’ll also have a permanent record of the customers paint surface, which can be used as a reference each time the car is polished.

Most paint thickness gauges work by sensing the distance between the sensor and the metal base material. That’s total distance, which would be the thickness of all layers (primer, base, colour, and clear coats) and any repainted material, etc. You have to take an educated guess as to how much each layer consists of.

Select substrate
F - for ferrous metals (steel and cast iron)
N - for non-ferrous metals (aluminium, copper, brass, etc.)
FN - for all metal substrates, gage automatically recognizes the substrate and takes measurement

Magnetic Induction - using this technology the thickness gauge utilizes non-destructive principles when measuring coatings on Ferro-magnetic substrates such as Steel and Iron. The coatings must be non-magnetic such as; paint, enamel, aluminium, chrome, copper and brass.

Eddy-Current - this technology utilize a non-destructive principle when measuring coatings on non-magnetic substrates such as; aluminium, aluminium alloys, bronze, copper, brass tin and rustproof weak magnetic steels. The coatings must be electrically insulating such as; paint, enamel, plastics, anodized coatings and ceramics.

c) Ultrasonic- an ultrasonic transducer 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. 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. In some circumstances, individual layers in a multi-layer system can be measured.

Most factory paint jobs range from 3.5 to 5.5 mils (87 to 137 microns) (this will vary between manufacturers) for this reason, it’s also recommended that paint be measured when buffing since you can’t see how much paint is being removed during the buffing process. If an insufficient thickness of clear remains after polishing premature failures such as fading or delamination may occur as the colour coat won't be protected from ultra violet (UV) radiation and a warranty issue may develop in the future. Such risks can be alleviated by monitoring and minimizing the amount of top coat removed, which is best done through quick and easy measurements with an electronic paint gauge, and maintaining a record on a paint thickness template.

German and Japanese cars: 4-5 Mils (1 Mil=1000th of an inch)
With the exception of:
Lexus-White and Tan: 5-7 Mils, Lexus- Black and Silver: 4.5-6 Mils
BMW: Silver: 6-7 Mils
FORD: Approx. 5.5-7 Mils
GM Cars and Trucks: Approx. 4.5-6.0 Mils, Jimmy’s and Blazers: approx 7 Mils
Chrysler: Approx. 5.5-7 Mils (Note Sebring hoods are fibreglass)
Dodge Cars: Similar to Chrysler
Dodge Trucks and newer Ram Pick-ups: Cab approx. Mils and the boxes approx 9 Mils
Jaguar: approx. 6-7.5 Mils (but they tend to vary)
Jeep Grand Cherokee: These read approx. 6-8 Mils, Wranglers: approx. 4.5-5.5 Mils

Note- the above are provided for information only

It’s interesting to note that painters must now demonstrate proficiency with an electronic paint thickness gauge in order to become certified to perform refinish warranty work for General Motors Corp. (GM) vehicles.

DeFelsko 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.
a) DFT Ferrous is ideal for measurements on steel panels
b) DFT Combo is available for measurement requirements on both steel and aluminium panels. With 3% accuracy and a 0.1 mil (2 micron) resolution
Either PosiTest DFT model provides the capability to measure the amount of paint removed while sanding and buffing. DeFelsko - PosiTest DFT - Paint thickness Gage measures coating thickness on all metal substrates
Or Detailers Domain - http://www.detailersdomain.com

c) PT200 Ultrasonic Thickness Gage - this revolutionary meter measures paint thickness over non-metals such as fibreglass panels, plastic bumpers and interior components, approved for use in BMW’s dealer equipment program – DeFelsko - PosiTector 200 - Ultrasonic coating thickness gage measures coating over concrete, wood, composite and more.

d) PosiTector 200 will work on composites (plastics, carbon fibre, fibre glass, etc). The ideal setup if memory functions for metals aren't important would be a DFT Combo for the metals and a PosiTector 200 B/Adv for the composites (these two PTM approx $1000).

e) PosiTector® 6000 Series (composites; plastics, carbon fibre, fibre glass, etc you will want the FN or FNS models as they work on all metals) rugged, fully electronic coating thickness gages use magnetic and eddy current principles to measure coating thickness on both ferrous and non-ferrous metals, accurately and quickly. SSPC PA2 feature set determines if film thickness over a large area conforms to user-specified min/max levels - PosiTector 6000 coating thickness gages, gauge, meter use magnetic and eddy current principles to measure coating thickness on both ferrous and non-ferrous metals.

DeFlesko Applications - Automotive Paint Detailing

f) Alibaba Coating Thickness Meter CM8828
Operating principle: Magnetic induction / eddy current (F / NF) measuring range: 0-1250um / 0-50mil
Resolution; 0. 1 / 1, Accuracy: + / - 1-3% n or + / -2. 5um, it meets the standards of ISO2178 and ISO-2360 as well as DIN, ASTM and BS. Suitable for the laboratory and for use in harsh field conditions The F probes measure the thickness of non-magnetic materials (i.e. paint, plastic, porcelain enamel, copper, zinc, aluminium, chrome etc.) on magnetic materials (i.e. iron, nickel etc.) . Often used to measure the thickness of galvanizing layer, lacquer layer, porcelain enamel layer, phosphates layer, copper tile, aluminium tile, some alloy tile, paper etc. The N probes measure the thickness of non-magnetic coatings on non-magnetic metals.

It is used on anodizing, varnish, paint, enamel, plastic coatings, powder, etc. Applied to aluminium, brass, non-magnetic stainless steel, etc Automatic substrate recognition - Colead Industrial Co., Ltd. China
Alibaba - Coating Thickness Meter Manufacturer exporting direct from China

TOGWT ™ Copyright © 2002-2008. Jon Miller, all rights reserved

[ZoranC]

Thank you again Dr. Jon!