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Thread: Clearcoat sanding technique for mirror finish

  1. #16
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    Quote Originally Posted by lmeddick View Post
    Seeing as it's alien to me at the moment, if you spray and get no peel ANYWHERE and you're doing a show car, does that mean assuming no runs etc that the finish is show ready without any sanding?
    A show car paint job is usually very close to perfection and that's normally not doable right out of the gun. Orange peel, dust nibs etc. are typical then sanding and polishing are needed to achieve perfection.

  2. #17

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    Quote Originally Posted by Len View Post
    A show car paint job is usually very close to perfection and that's normally not doable right out of the gun. Orange peel, dust nibs etc. are typical then sanding and polishing are needed to achieve perfection.
    Have you ever seen the waves in the last picture I posted on a car with an otherwise completely levelled paint job? The cause puzzles me but I know in some areas of my test hood I'm pretty sure I'm rid of them after going doing to 400grit. Maybe it's really deep peel that I'd never otherwise been able to level due to previously using no less than 1200

  3. #18
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    Quote Originally Posted by lmeddick View Post
    Have you ever seen the waves in the last picture I posted on a car with an otherwise completely levelled paint job? The cause puzzles me but I know in some areas of my test hood I'm pretty sure I'm rid of them after going doing to 400grit. Maybe it's really deep peel that I'd never otherwise been able to level due to previously using no less than 1200
    Those "waves" in post #14 appear to be orange peel that was not fully removed. You should be able to use a block and some 800 or 1000 grit wet sandpaper to level the surface then some 1500, 2500 then polish to get a flat finish. You're real close to perfection so starting with a more coarse paper would do the trick.

    When you start sanding don't put a lot of pressure on the block so that you don't push into the low areas, you want to stay on top of the high spots and sand them down level with the low spots.

  4. #19
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    Quote Originally Posted by Len View Post
    I never get "waves", what do you think is causing them? I got orange peel before I used my Sagola but not waves.
    i guess the waves are just a form of peel, i don't know how else to describe it. you really have to look hard to see them. there's been discussion on it before so i'm trying to use the suggestions i read from previous posts to help me out.
    i'm using a sagola i bought from you for this project and the finish straight from the gun is probably the best i've ever done. but i have been sanding on this thing for so long that i think i might be just too picky. i kind of think my paper is suctioning down in the low spots when i'm trying to cut the high spots. i'm trying a few different things to combat this and using a very hard block in certain places is letting me wrap the paper very tightly on the block and get things flat.
    could soaking the paper too long let it stretch and conform to the panel too much? i usually soak the paper overnight.
    b marler

  5. #20
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    Quote Originally Posted by bmarler View Post
    i guess the waves are just a form of peel, i don't know how else to describe it. you really have to look hard to see them. there's been discussion on it before so i'm trying to use the suggestions i read from previous posts to help me out.
    i'm using a sagola i bought from you for this project and the finish straight from the gun is probably the best i've ever done. but i have been sanding on this thing for so long that i think i might be just too picky. i kind of think my paper is suctioning down in the low spots when i'm trying to cut the high spots. i'm trying a few different things to combat this and using a very hard block in certain places is letting me wrap the paper very tightly on the block and get things flat.
    could soaking the paper too long let it stretch and conform to the panel too much? i usually soak the paper overnight.
    Soaking the paper is a good thing and wrapping it around a hard block should stop it from following any surface irregularities. When we do a show car that is the process we use so it should work for you but it may take some practice.

  6. #21

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    Quote Originally Posted by bmarler View Post
    i guess the waves are just a form of peel, i don't know how else to describe it.
    Agreed, it's like looking at Peel except a very minor version and I'm going to go with Len's explanation. I can't see it being caused by uneven sanding like I initially thought (not unless you really do something stupid) because you can guarantee that on the most micro/nano levels, no finish will ever be laser straight. Between sanding, stroke length, then polishing the sanding marks out, it is just not gonna happen. There are so many variables. What if the buffer was 50% overlap that pass and 60% the next? What if some of the abrasives broke down a bit quicker? Then consider maintaining this across the WHOLE CAR. And what if the next polishing pad is not 100% factory identical to the other if you swap between panels? Even then the initial spreading pass will differ to after its more saturated. I think the flattest finishes will still be slightly uneven but to the point we'd never notice.

  7. #22
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    Here's an above average finish we did a couple years ago. No waves and no peel because we sanded and polished.




  8. #23

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    Quote Originally Posted by Len View Post
    Here's an above average finish we did a couple years ago. No waves and no peel because we sanded and polished.

    That upclose picture, wowzer!

  9. #24
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    Sounds like urethane wave that you are seeing.

  10. #25

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    Quote Originally Posted by xtremekustomz View Post
    Sounds like urethane wave that you are seeing.
    Does anyone have any pictures of urethane wave?

  11. #26
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    Quote Originally Posted by xtremekustomz View Post
    Sounds like urethane wave that you are seeing.
    i'm sure you're right, i've read all the posts on that subject and am working through the suggestions to see what works for me. this car was painted in pieces and some panels have been sitting for over a year, the most recent paint is 2 months old. i purposely let the paint sit so it would fully shrink before sanding. its ppg single stage, good quality and sands pretty good. luckily it's a small car or i'd be sanding for another year.
    b marler

  12. #27
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    Quote Originally Posted by bmarler View Post
    i'm sure you're right, i've read all the posts on that subject and am working through the suggestions to see what works for me. this car was painted in pieces and some panels have been sitting for over a year, the most recent paint is 2 months old. i purposely let the paint sit so it would fully shrink before sanding. its ppg single stage, good quality and sands pretty good. luckily it's a small car or i'd be sanding for another year.
    Yeah there are some that sand with 400 grit to smooth out the wave and work their way up to 5000 but you better have plenty of material to do that. I've gone as low as 800 myself.

  13. #28

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    Quote Originally Posted by Len View Post
    Here's an above average finish we did a couple years ago. No waves and no peel because we sanded and polished.



    Nice job Len on the polishing! Did you only use Dura block for your hard blocks on the polishing? If you used a different hard block please share. Also how did you get in those tight radiuses.

    Ken

  14. #29
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    Quote Originally Posted by convertcuda View Post
    Nice job Len on the polishing! Did you only use Dura block for your hard blocks on the polishing? If you used a different hard block please share. Also how did you get in those tight radiuses.

    Ken
    By the way the fogginess of that reflected light (bottom picture) is because it has plastic film in front of it.

    If the paint is applied well the sanding and polishing is a lot easier than if their is a lot of orange peel. In most cases the body work is done well and blocked level using several different size and shaped blocks. The primer is applied, guide coated and block sanded using mostly the 5" block unless there is something that needs more correction and a different block. The paint is also sanded with the correct block especially in those tight bends. I like the "Tear Drop" block which I cut into one third so that I had a small, medium and another full size block. I like putting coarse paper on that rounded edge of the Tear Drop block for sanding filler in a con-curved area.


  15. #30

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    Thank You!

    Ken

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