Quote:
Originally Posted by tmclssns
@TOGWT: I follow some detailing fora and I noticed that often times more than one micron is removed from the clear coat to achieve correction.
I've never really polished out deep scratches that were white / catched your finger nail beyond the point of full correction. Most of these scratches were "invisible" unless you knew their exact location.
However I've seen Clark from Polished Bliss remove several microns of paint to achieve correction, which would also correct a scratch of 2 micron deep for instance?
|
Paint Removed by Polishing
When an abrasive polish works on the surface of paint it uses aluminium oxide spheres, suspended in an oil / water emulsion that provides surface lubrication, and uses a mechanical process to abrade the surface of the paint down to the level of the bottom of the scratch.
Experience will teach you how your polish/pad combination ‘feels’ as it goes through the various stages; i.e. cutting, to polishing stage and finishing stages, just when the polish lubrication has dried up (this is usually when a polish starts to produce ‘dust’), this is where you stop, wipe off the polished area, inspect the paint surface and either clean the pad, apply more polish or change it for a clean fresh one.
Using a medium abrasive polish and a rotary polisher will remove approximately 0. 1 Mil (3µ ) Range 0.8 – 1.1 Mil (20 – 28 µ) from the paint surface (typically 4 passes at 1500-1800 RPM) but there are many variables such as the abrasive grade of the polish or compound and speed and pressure used that may affect the paint removed) These numbers should be checked with a paint thickness gauge (PTG) There comes a point when you must judge wither removing a scratch will compromise the clear coat and if so you’ll have to ‘live’ with the imperfection.
A clear coat thickness is approx 2-3 Mils (50 - 75 µ) 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.
If you have reservations about the amount of paint surface removed or the amount of paint coating remaining the use of a paint thickness gauge (PTG) is arbitrary
Note: 1 µ (micron) is 1/1000th of a millimetre or 0.0393700787 Mil or 0.001 of an inch
• 200µ 8 mil + 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
These numbers are offered as a guide only, as there are too many variables to provide any more than an approximation.
Paint thickness will often depend upon the OEM paint specification, which can vary by vehicle assembly plant. It’s interesting to note that painters must now demonstrate proficiency with an electronic paint thickness gauge (PTG) in order to become certified to perform paint refinish warranty work for General Motors Corp. (GM) vehicles.