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Correcting my first DIY bumper, Experts I need your input! General help required

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  • Correcting my first DIY bumper, Experts I need your input! General help required

    Apologies for the long post in advance, I'm hoping the more information the better for anyone to help me out with this!

    So I painted my first bumper after watching a few hours of process online, researching for a few more hours, the arctic silver matches great from a rattle can and I've got really lucky! However the 2k Spraymax clear cans had some pretty bad flow and I have some standard orange peel all about:

    After seeing the pretty bad finish I got to work learning what I could about the correction I can do after the fact to get a better finish. I went and bought pretty budget equipment because I'm not too likely to do this much more often in the near future.
    I first wet sanded with the block using p2500 grit (something like 1200 grit US? stupid that you have to convert) up to about p7000 (I can't find info online about wtf P standard grit is compared to normal grit up to this amount).
    Then used a dual action polisher, meguairs 105 cut with a medium firm pad and 205 mirror polish with a really soft pad and the techniques I saw online (making overlapping passes, directions, speed and pressure they recommend) and I end up with this:

    I'm fairly satisfied with the improvement considering I'm just DIYing with online info and random equipment. My only problem is despite the finish I got I can still see a small amount of pretty big fine scratches kind of isolated around in random spots, and then what look like some smaller soft cuts left over from sanding.

    I'm here to ask what this somewhat marred finish comes from, did I not sand through enough with the higher p7000 grit? When exactly do you know youre done sanding? I was trying to get an even looking scuff but it's tough to judge as a newb. I'm thinking I maybe go too much with the rough 1500 equivalent grit or perhaps contaminants get underneath and deep scratch in terms of those longer isolated scratches left behind.
    Maybe I need another buffing pass? or that my buffing technique needs to be more aggressive, I've tried using a wool pad too for this and i seem to get the same issues. Can anyone diagnose this for me and give me some tips? the scratches basically look like isolated long scratches that didn't sand out somehow and the cuts look like a very small crosshatch texture from sanding that doesn't look very sharp, almost like soft edged cuts.
    Also if anyone is from the UK and has a set routine with UK standard sandpaper that I can use I'd appreciate that. Any and all input about the process and technique that you have would be appreciated, and if I'm chasing a perfection that's probably not warranted as its a diy bumper that'll get scuffed anyway feel free to let me know!

    cheers guys

  • #2

    the big fine scratches- that reads like it could be 2 issues. 1- contaminated sandpaper. meaning, a piece of grit on the sandpaper leaving deep scratches. or 2- not refined enough. when i sand frash clear, i switch directions between grits. an example- start with a ///// direction. with the next grit, go to a \\\\\\\ direction. that way i have a better chance at seeing ive refined the scratch pattern from the last grit.
    when i know im done sanding: if i have something that has orange peel like you have, first grit i use a had block backer and know im done with that grit when there are no more shiney spots. then switch grits and direction. good lighting helps me see the refinement. a guide coat can also be used, which how to guide coat can be a topic in itself.

    the marred looking finish is more than likely from not enough buffing with the m105. its not so much marred as you havent buffed enough to refine the finish and bring the gloss back.
    the m105 should bring the finish up to a high gloss.