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Thread: Deep scratch removal (key marks)

  1. #1
    Regular Member Little John's Avatar
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    Default Deep scratch removal (key marks)

    I know this seems to be a problem that people now seem to think it is OK to "key a car" either for kicks or disgruntled people seem to do it if you annoy them. Also with insurance costs more and more people seem to drive off if they rub your car leaving parting spaces usually on the corners where the plastic bumpers move to absorb the impact but the paint usually either gets removed or scuffed.

    So, the general rule is that if you can feel the scratch by running your finger nail across it then it requires painting in bodyshop which the going rate seems to be about £100 per panel requiring painting or part painting now most keying runs down the side of a car so front wing, 2 doors and the rear quarter they can result in a fair repair bill that usually isn't worth making a claim on insurance due to excess and the premium increase the following renewal.

    So what I always do is "have a go" if it doesn't work it goes to the bodyshop and I have lost a few hours of my time trying to sort it, if it does work I have saved a few hundred quid. Remember I already have a meguiars G220 machine polisher and a selection of abrasive polishes to work with and a paint thickness gauge.

    With all polishing it is a case of improving the appearance be it a scratch, swirl marks or dents. Swirl marks are easy (with a machine) scratches easy again with a machine dents no machine will sort them but usually there is some paint transfer or a scratch in there that makes them more noticeable Now the reason scratches and swirl marks are seen is because the light catches the edges of the scratch so if you can remove the sharpness of that edge the light no longer catches the edge so the appearance of the scratch or swirl mark is removed or softened, so it isn't always necessary to remove the scratch fully just soften the edges which can usually be done by hand with the correct polishing method.

    So the equipment used
    Meguiars G220 dual action machine polisher other machines are available
    Sonus 4" spot polishing pads using the smaller pads helps concentrate the polish on to the part your polishing to increase cut and get better results.
    Polishes I used Meguiars #83, 3M Fast cut plus and 3M Ultrafina
    Meguiars last touch as clay lubricant, yellow poly clay but again any clay can be used, I should have used sonus green or bilt hamber soft I couldnt find either of them in the car the poly clay can be difficult to keep soft when its cold.
    CM 8828 paint thickness gauge essential if your working on someone else's car with a machine polisher, its not perfect but it allows me to take an educated guess at the amount of clear coat available.

    Yes thats £400+ worth of kit and if your only looking after your own car its expensive, you will be able to polish the whole car, remove swirls etc and have a really good looking vectra, you will also be able to maintain the finish each year givieng it a go over with the machine if needed. Over the last few years I have had the machine I think it has paid for itself just in the scratch repair/improvements I have done for people.

    The process
    The whole car was washed using the 2 bucket method
    I would normally clay the whole car but just did the areas I was polishing as the poly clay is quite hard in cold conditions and it was freezing.
    I then washed the clayed sections again
    Dried the work areas.
    Then the polishing
    Finishing polishing
    Wax/sealant protection

    So what do we have
    The front passenger side corner, someone clipped the corner in a car park, scraping the edge of the wing but removed some paint from the corner of the bumper where it meets the wing


    Drivers side, front wing, part of the key attack starting just behind the wheel arch runs over the arch and on to the front bumper.

    the front part of the wing and bumper

    the whole wing


    car park door ding someone opened a door in to the side of the car, there is a dent with scuffed paint and some paint transfer and a little bit of key scratch just below it.

    rear wing and bumper, the person just seemed to not like wheel arches and bumpers.



    Paint thickness read, 132 microns I checked a few areas of the car and the reading were between 135 and 129 which is a very even coat, I also measured in the door shuts as this area usually gets less clear coat than the rest of the car so that measurement gives me an indication of how much clear coat is on the other parts of the car, the door shut read between 79 and 69 microns which give me quite a lot of clear coat to play with but I don't want to remove too much. unfortunately my paint thickness gauge will only measure the total thickness of the coating (primer, colour and clear coat) on metal panels not plastic and plastic bumpers and wings on the clio make it a little more difficult to know how far to push the polishing.


    Anyway the front corner first, I could do nothing with the paint removed but I tried the polishing first with meguiars #83, working the polish on the machine applied 4 large pea sized blobs to the pad and dabbed it on the area, I then set the machine to speed 1 and switched it on a few quick passes over the area to spread the polish, then stepped up to speed 3 and applied enough pressure to slow the spin of the pad to 1 maybe 2 rotations per second, this is a dual action machine so it oscillates also and that gives cut as well.
    After about 3-4 minutes working the #83, an improvement yes and the lighter marks have almost gone, the improvement to the deeper scratches was done by softening the hard edges of the scratches.


    I then changed the polishing pad to another white polishing pad and stepped the polish up to 3M fast cut plus which is quite an aggressive polish with a heavy cut compared to the meguiars #83, the extra cut was required as the #83 just wasn't enough, if I had repeated the process with #83 3 maybe 4 times then the result would have been similar but That would take all day, It is always good to try a lower polish the more paint left on the car the better there is no point hitting it with a sledge hammer when a toffee hammer will do. All that is left of the scuff is a small nick just above the removed paint. Yes I could have removed that but would also have removed more paint on the surrounding area so it is a case of not really needed.

    The same process was used on the other areas, but missing out the #83 step, I did 2 passes with the fast cut plus on the rear wheel arch I broke the area up in to 2 sections as the scratch was about pretty long again to increase the amount of cut by concentrating the area.


    the 2 passes removed about 11 microns of paint, the long scratch was almost all removed, I was left with about 8cm of scratch visible if you are looking at from about 20cm away. The appearance was reduced and only visible from certain angles


    From about 1m away it is less visible, again further polishing could remove those marks but is it worth removing another 20% maybe of the clear coat to remove that which would then make it 60% the original estimated level?


    This is where the paint transfer and scuff was from the door ding.


    The front wing from the normal viewing distance

    The rear arch, the mark is just about visible from this angle

    and this angle?


    Same done on the front wing, after the first hit

    The 2nd hit cleared the whole lot


    After the polishing with the fast cut plus there was some holograming which are very fine compacted light swirl marks in the clear coat, I used 3M ultrafina which is a very light polish to remove those.

    Back to the original thing of trying to improve the apearance and save money on bodyshop repairs, in this case it was 2 front wings, the front bumper on both sides, the rear bumper passenger side, the rear panel over the wing and the dent in the middle. 5 panels would have needed bodyshop attention, now the 2 wings and rear bumper are perfect, so that has saved £300. The rear panel is pretty close but still needs the dent sorting anyway so not too bad?

    I hope you found this useful, if you have any questions post below and I and the others who can do will help out I'm sure.

  2. #2
    Ex Vec-C Admin Deztroyer's Avatar
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    hi mate,

    as i said on the other thread - excellent how2 and well worth it's own thread - well done again

    regards

    Dez

    0-Large smile ......every time it's driven

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    Regular Member parsco's Avatar
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    Nice write up John

    I haven't had the chance to have a go at some 'deeper' scratches as of yet. But I'm always up for having a go and would need to get some more abbrasive polishes. The write up gives me some more confidence and a better idea, cheers

    Would be great to meet up sometime mate so I could learn some more off you

  4. #4
    Regular Member Little John's Avatar
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    parsco, its a little far for both of us to travel I think Manchester to Cambridgeshire. I'm going over to Tony's (Autoshine SV) place on the 16th for his demo day up in Wakefield.

    I get plenty of practice on deeper scratches unfortunatly with 3 black cars and a mate who changes his car every 6000 miles for a new one people don't like new cars for some reason. The process is the same as swirl removal but more concentrated to a smaller area and useing somthing like fast cut plus or Farecla G3 for that extra bite. You can see in the door ding finished picture how localised the polishing was as bellow the area you can see the swirls from its monthly brush wash, there was no way I was doing the whole car as I had seen how it gets washed, it was just pointless.

    If you do decide to head up to Manchester I know a few places that can almost guarentee you some scratches to practise on if you park there for 10 minutes.

  5. #5
    Admin & Merchandise Manager bigmac's Avatar
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    Great write up this is what this forums about,everyone sharing the knowledge

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    Regular Member Tadpole's Avatar
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    Just hope I never need this info thanks for the 'How2' s up from me ................

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    Regular Member Lump's Avatar
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    great write up fella, and to be fair there is nothing to be worried about, get stuck in and have a pop at those deeper marks. and parsco, if you need some compounds let me know

  8. #8
    Regular Member parsco's Avatar
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    Quote Originally Posted by Lump View Post
    great write up fella, and to be fair there is nothing to be worried about, get stuck in and have a pop at those deeper marks. and parsco, if you need some compounds let me know
    PM'd

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