Typical OEM Paint Thickness
Original equipment manufacturers (OEM) supply a specification to their paint suppliers that establishes a minimum film thickness necessary to ensure paint durability and enable them to provide a guarantee
• E-Coat ~33 µ (1.3 Mil) - an anticorrosion coat applied to both sides of the steel to prevent corrosion
• Primer ~18 µ (0.7 mil) - Initial protection layer with texture to assist the pigment layer in bonding to the metal beneath
• Base Coat ~15 µ (0.6 mil) - The basecoat is usually 0.5 to 1 mil thick
• Clear Coat ~48 µ (1.9 mil) - The clear coat provides gloss plus physical protection from the elements, including ultraviolet (UV) radiation, which is situated in the upper 1.0 – 1. 25µ (0.04 - 0.05 mil)
A micron (µ) is a metric unit that equals one millionth of a meter, or 1/1000 of a millimetre. A micron is much smaller than a Mil. One (µ) micron is roughly 1/80th of the thickness of a human hair. There are 25.4 millimeters in an inch and a micron is 1/1000 of a millimetre. Using the micron measurement gives you a much better idea of paint thickness because it's so much smaller.
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)
Be cognizant that ultra violet protection removal is not a liner process; and the first paint renovation will remove the most UV protection, therefore the above are probably conservative estimates. Two variables need to be established; how much clear coat is available and how much clear coat can be removed without compromising the paint systems long-term durability / paint warranty
A paint thickness reading of > 4 Mil ( 100 µ (Microns) is reasonably safe for polishing. 3 – 3.5 Mil ( 80-90 µ) I wouldn't use anything stronger than > 2000 grit polish, 2.75 – 3.0 Mil (70-80 µ) > 2500 grit polish and under 2.75 Mil (70 µ) use a glaze. The readings tend to vary from panel to panel and are thinner towards the panel edge.
• 200µ + can be expected on older cars that have been hand painted or a re-painted vehicle
• 100 – 200µ 4 – 8 mil - normal paint thickness
• 80 – 100 µ - 3 – 4 mils, thin paint
• 80 µ < - less than 3 mil, very thin paint