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how many buffs

 
Old 07-13-2010, 04:00 PM
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Priceless
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Question how many buffs

i have a couple of superficial scratches and considering having my car buffed to rid them. however, should i wait for more scratches? is there a low limit to how many buffs a 1996 993 can take? i don't know how many she has had in the past???

thanks in advance.
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Old 07-14-2010, 06:26 AM
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Most pro detailers will check the paint thickness before using a machine polisher to ensure there is enough clear coat available for correction.

To remove a scratch means that the paint must be levelled; when a paint renovation detailer uses this term it really means that they are going to be abrading the surrounding paint area that that contains the defect (scratch, swirls, surface marring, etching, pitting, etc.) It is possible to remove a scratch by abrading the clear coat to a lower level then the base of the scratch, which will remove clear coat, just be aware of how much you remove, as you don’t want to compromise the paint systems protection.

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 + 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 in order to become certified to perform paint refinish warranty work for General Motors Corp. (GM) vehicles.

Last edited by TOGWT; 08-01-2011 at 05:27 AM.
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Old 07-14-2010, 06:42 PM
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thanks for the gr8 advice and information
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Old 07-17-2010, 05:15 AM
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Originally Posted by TOGWT View Post
Most pro detailers will check the paint thickness before using a machine polisher to ensure there is enough clear coat available for correction.

To remove a scratch means that the paint must be levelled; when a paint renovation detailer uses this term it really means that they are going to be abrading the surrounding paint area that that contains the defect (scratch, swirls, surface marring, etching, pitting, etc.) It is possible to remove a scratch by abrading the clear coat to a lower level then the base of the scratch, which will remove clear coat, just be aware of how much you remove, as you don’t want to compromise the paint systems protection.

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 + 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 in order to become certified to perform paint refinish warranty work for General Motors Corp. (GM) vehicles.
+1...great info Jon.
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Old 07-17-2010, 10:58 PM
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Originally Posted by TOGWT View Post
Paint thickness will often depend upon the OEM paint specification.
What would that be on a Porsche?

I read somewhere that they put on x number of coats and a clear coat. Do their "solids" have a clear coat? Some say yes; others say no. I haven't taken a soft white cloth with polish to my paint yet to find out.
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Old 07-18-2010, 06:24 AM
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Clear Coat Thickness

Modern clear coat paint finishes are so good today that they lull people into thinking that vehicle paint has protection and shine when in reality there is not really much there, other than the clear coat that has a thickness of 1.5 – 2.0 Mils. 1 mil = 0 .001", 1000th of an inch or 25.4 µ. As a point of reference a sheet of copy paper is 3.5Mil (89 µ) One micron is roughly 1/80th of the thickness of a human hair (hair thickness depends on hair colour/ethnic origin etc)

Most vehicle paint film systems (127 - 178 µ) comprise a Primer coat of 2Mils (50 µ) a Colour coat of 1-2Mils (25 -50 µ) and Clear coat 2-3Mils (50 - 75 µ) 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, there is ultra violet (UV) protection all the way through the paint, but the majority of it rises to the top with the thinner solvents and particles. So the removal of a paint UV protection is not a liner projection. As a point of reference a sheet of copy paper is 3.5Mil (89µ) a surface scratch that will `catch' your fingernail is approximately 0.004 Mil (0.01µ) deep will usually require wet sanding and refinishing.

A paint thickness meter (PTG) would give you a value for the thickness of paint on your vehicle

Last edited by TOGWT; 08-13-2011 at 05:07 PM.
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Old 07-31-2011, 09:25 AM
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Default Re-clear Coating

Have been going through a search on buffing out a clear coated paint and the question is always "how much clear is left"? So, my question is this: if your paint measures out to be "thin", but is visually still "good", can you just re-clear the surface (after proper prep, of course) so that you have sufficient paint thickness to deal with? If the base coat color is still intact, "adding" clear to the paint thickness should not impact the car's color, but would restore the paint overall thickness, right?

Just a thought.
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Old 08-01-2011, 05:29 AM
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Clear coat is paint that has no pigmentation (colour) added. Many show cars have 3-5 layers of clear coat added to ensure a 'usable' paint thickness
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Old 08-01-2011, 05:41 AM
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Originally Posted by IXLR8 View Post
What would that be on a Porsche?

I read somewhere that they put on x number of coats and a clear coat. Do their "solids" have a clear coat? Some say yes; others say no. I haven't taken a soft white cloth with polish to my paint yet to find out.
There are more than one paint suppliers for Porsche vehicles, so dependent upon paint supplier, specification and paint age this will vary.

Some 'solid' colours (Red, black, yellow,white, etc) are single stage (not clear coated) some of these colours use a less dense (soft) paint.

Diagnosis is the key; not guesswork. Before you start to polish a paint surface find out its thickness, single stage or clear coated, dense or less dense (hardness).
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Old 08-12-2011, 06:43 AM
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Originally Posted by earossi View Post
Have been going through a search on buffing out a clear coated paint and the question is always "how much clear is left"? So, my question is this: if your paint measures out to be "thin", but is visually still "good", can you just re-clear the surface (after proper prep, of course) so that you have sufficient paint thickness to deal with? If the base coat color is still intact, "adding" clear to the paint thickness should not impact the car's color, but would restore the paint overall thickness, right?

Just a thought.
Clear Coat Thickness and Paint Removal by Polishing - http://www.autopia.org/forum/guide-d...polishing.html
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