In the spirit of sharing...

[Carn]

Ouch...nasty scratch, what can we do to fix this



What have we done



Thats better

[freerider]

WOW thats extreme clear coat removal what grit was that done with?

[TOGWT]

Just for information / future reference

Thickness - a clear coat has a thickness of 1.5 – 2.0 Mils, removing more that 0.4 mil (0.0004") of clear coat will cause premature paint film failure. As a point of reference two sheets of Saran wrap placed on top of each other measure 1.5Mil (0.0015") a surface scratch that will `catch' your fingernail is approximately 0.004" deep and will usually require wet sanding and refinishing. 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 (See also Paint Thickness Gauge (PTG))

[Carn]

@ Freerider, single pass with 1500 grit water paper refined with a single pass of SIP and single pass of 106FA

@ TOGWT do you have any idea or reference as to how much of a paints thickness is removed by regular polishing with various different combo's ? For example Menz Power Gloss on a wool pad, or SIP on an Orange LC pad ?

Many compounds are listed as being able to remove 1500grit sanding marks so I would assume they remove as much clear as what wetsanding with a similar grit would, or am I mistaken ?

For reference this car has had paint work done at some stage as evident by the overspray on several plastic parts

[TOGWT]

1. TOGWT do you have any idea or reference as to how much of a paints thickness is removed by regular polishing with various different combo's ? For example Menz Power Gloss on a wool pad, or SIP on an Orange LC pad ?

There would be so many variables, 'hard' or 'soft' paint age of paint, mfg, etc, etc

2. Many compounds are listed as being able to remove 1500grit sanding marks so I would assume they remove as much clear as what wetsanding with a similar grit would, or am I mistaken ?

You are not mistaken, that's why 'grit number' was chosen as the "benchmark" for scratches and scratch removal

[JLs Detailing]

Nice work David. Its amazing what a little piece of wet sandpaper can do, huh. I was always apprehensive about wet sanding and then finally tried it out and was amazed at what could be done with it and the right polishes afterward.

[MeTsU]

Great stuff there David! Glad to see that beast of a scratch was removed!

[calypso]

Approx how many passes with the 1500 did it take to remove the scratch?

[Carn]

I didn't count the actual passes but basically sanded them until you could just barely see where the original scratch was (as can be seen in pic 2 of my original post). What was left of the scratch was polished out with the 2 passes of Menz. I would advise caution when attempting this as it is very easy to go through the clear coat, ideally a proper PTG is required but they a little pricey at the moment

Also worth noting is that whilst these scratches appear to be quite deep they didn't look to be right the way through the clear coat, if you can see the base coat then avoid sanding at all costs (all IMHO of course)

[calypso]

Buy the cheapie gauge, then tell us all what its like.
http://www.harborfreight.com/cpi/ctaf/Di...mber=95520

[Carn]

Thanks but no thanks, penny wise and pound foolish, etc

[calypso]

It cant be thaaaaaaat bad.

[Carn]

(25-11-2008 11:01 PM)calypso Wrote:  It cant be thaaaaaaat bad.

Famous last words

If it doesn't work I will be sitting with the Shield Obital of paint thickness gauges

[TOGWT]

I've got to agree, especially on precision instruments like a PTG-you'll only get what you pay for.

[crazygolfer]

(25-11-2008 07:07 PM)calypso Wrote:  Approx how many passes with the 1500 did it take to remove the scratch?

that lil sanding block u got works gr8 4 scratches like that.sum1 scratched my bonnet with a key and that lil block did the trick.

[calypso]

There is a full review on the megs site, ill find it and post the link. From what they said its not bad, its just cant get consistent readings. So if you did the same spot twice it would always very by a few microns.
But its still alot better then guessing. Even a machine that just said "thin, med, thick" would help.

[TOGWT]

A paint thickness gauge for use in the detailing industry requires fine measuring resolution in increments of 0.1 mil (0.0001= inch) is typical. Therefore you should choose a paint gauge with a minimum 3% accuracy and a 0.1 mil (2 micron) measuring resolution.

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 - http://s3.photobucket.com/albums/y88/TOG...n9br-3.jpg

For more information see “Paint Thickness Gauge (PTG)” one of a collection of detailing articles on DetailingWiki; (Wikipedia® is a registered trademark of the Wikimedia Foundation) a series of informative, knowledge based, unbiased articles dedicated to automotive detailing