How do I know if my clearcoat is too thin?

Hey All,

So I've done two comprehensive polishing jobs on the hood of my '08 Dodge Charger using a porter cable.. Both times have been with a orange pad and Adams Swirl and Haze followed by a white pad and Adams Fine Machine Polish.. I used a fair amount of pressure on the pc

I think these two Adams product are pretty safe, but now I'm using menzerna SIP and 106 (my paint is not ceramic or super hard).

Can I ever polish "too much" with menzerna and a pc? and if so how can I know?

Thanks!

 

you can definitely over polish a vehicle. The best thing to do is practice proper washing techniques to help minimize the marring and swirls induced into the paintwork. By starting with that it will help prevent you from having to polish the vehicle a lot. Most new cars have a fair amount of clear coat and using stuff like 106 really isn't bad . . . . . . SIP isn't super bad either but if every other month you are banging your car with M105 and a wool pad you will run out of clear rather quickly.

You can generally eyeball your clear coat to know if basically you have some left or not as you will know when you tear through it but the best way to get a accurate answer to your question is to purchase a:

PTG - Paint Thickness Gauge

or perhaps find a member on the forum who resides near you and is willing to let you borrow, rent or lend a helping hand in measuring your clear . . . . . might make a new friend out of it.

Hope that helps.

 

Hit the nail on the head.

 

hehehe thanks man.

 

Good advice there. A PTG is worth its price for the peace of mind alone. They had cheap ones on close out at Harbor Freight. To know the clear thickness, measure in an area like the inside deck lid and compare it to a finished surface. That difference will be the cc thickness. As a general rule of thumb, over 100 microns is good, under is problematic. 110 is even a better # to use.

 

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Why Use a PTG?

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

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 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

These numbers are offered as a guide only, as there are too many variables to provide any more than an approximation.

Note: 1 µ (micron) is 1/1000th of a millimetre or 0.0393700787 Mil or 0.001 of an inch
• 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

Ultra violet protection (UVR) a clear coat paint (isocyanate polyurethane) provides the colour and base coats with protection, and usually has UVR protection added in the final coating; this tends to migrate towards the upper level of the clear coat (this is why it’s important to check how much of the paint surface you are removing with an abrasive polish)

Removing more that 0.5 mil (12µ) of clear coat will cause premature paint film failure as UV protection percolates to the top of the clear coat. UVR protection is a sacrificial / renewable component; this is due to the UV protection layer being degraded by exposure to the elements (sun, sand, road or sea salt, and etc) it is also water miscible, so it is imperative that you renew it and needs to be re-applied on a regular basis (dependent upon location climatic condition)



An extract from “Paint Thickness Gauge (PTG)”, one of a series of 117 unbiased Detailing Technical Papers, a library of educational materials that has become the #1 reference for car care on the Internet

Chances are you'll learn something about detailing if you read any of these; although these articles will not improve your detailing skills, lead to a successful business or change your life. Applying what you learn from it, however, will. That's where your commitment comes in - you need to make a commitment to yourself right now that you will take action on what you learn.

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You can polish to hard but would take a while to have this happen and would need to be a more aggressive product when using the PC.
x2 on someone saying find someone local to check with a paint gauge.