how coarse can you go?

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  • September 14, 2011 at 11:47 pm #32888

    in regaurds to final sanding a black primer to be top coated with a solid black? ive covered 400 easy without excessive build up. 320? 220!? anyone?

    September 14, 2011 at 11:58 pm #32889

    Why do you want to go coarser?

    If you think it will adhere better it won’t.

    September 15, 2011 at 12:15 am #32893

    lets see, to save time, extra sand paper not used, reduces dust, improves shop air quality, reduces possible dust in the finish, extends shop filter life, saves elecricity for the da, saves phyical energy, saves your lungs from breating in extra dust….i can go on for quite a bit. i think why not would be the better question

    September 15, 2011 at 12:28 am #32894

    Its kind of a vague question.

    It really depends on the product you are using. Some base coats will cover 400…some I have used barely cover 600. Some single stage Polyurethanes I have used would cover 320 just fine.

    Most paints say in the tech sheet what grit the substrate should be finished with. Stick to what the tech sheet says, don’t need the scrathces showing up…or sinking in down the road.

    September 15, 2011 at 12:32 am #32895

    Personally i wouldnt go any further than 400

    September 15, 2011 at 1:10 am #32896

    I dont see enough of a difference in dust, material or time savings from say 320 to 400-500. But I see what direction you were heading with your question. I wasn’t sure if it was for your reasons listed or if you thought it would bite better.

    To give you another side to your answer, you retain more gloss sealing over a P400 scratch vs a P320 scratch. Same with basecoat but with finer grits. Once the finish is cured it will pull tight around the edges and sink into scratches. This can cause some loss of gloss if the sand scratches under are too deep.

    September 15, 2011 at 1:33 am #32897

    Just wet sand if you are concerned with dust :pcorn:

    September 15, 2011 at 2:51 am #32898

    shoot just skip the sanding all together if ya really wanna save time an money :nothingtoad

    September 15, 2011 at 8:51 am #32914

    [quote=”bondomerchant” post=22402]shoot just skip the sanding all together if ya really wanna save time an money :nothingtoad[/quote] YA thats what I want to do :nothingtoad

    September 15, 2011 at 10:07 am #32917

    the tech sheet- the tech sheet…. ya ya i hear ya. reminds me of my ol teacher. i agree tho, indeed the tech sheet should be followed close as possible… i was just sharing my results from using 400 couple times.

    the times that a reaaally reeeally wish i knew if 320 will cover is when im sanding down mesh style rims with all sorts of curves and cracks with clear peeling off and those grills with hundred verticle lines spaced 1/8 inch apart..

    September 15, 2011 at 3:44 pm #32920

    if you are sanding down peeling clear with 320 then you have a problem. :pcorn:

    September 15, 2011 at 8:18 pm #32928

    We don’t go any higher than p320 on anything except blend panels in our shop. Blend panels get p800. Everything sanded to p320 gets sealer, base, clear. Nexa auqabase plus.

    September 16, 2011 at 3:12 am #32934

    why dont you sand with 320 than give it a quick scuff with 400. Personally i seal everything that i paint because with the Nexa line the sealer is also the value shade.

    September 16, 2011 at 6:21 am #32938

    Seriously why kid yourself,if you think you are going to cover up scratches with base coat you are in for a shock.What happens when all the solvent evaporates from your basecoat?the scratches will still be there,it might take a week to 6 months but they will still be there.Old saying,”what there when start there when finished” there is no short cut for pre paint prep done properly.
    There is also a huge difference between 320 on a machine vs hand sanding with 320,the latter will be too coarse.A good rule of thumb is either 400 wet or( dry on machine) if you are sealing(any color) or 600 wet or( dry on a machine) if you are not sealing.

    September 17, 2011 at 4:20 am #32962

    Go 320 and then 400 by hand. nothing courser than 400.

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