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Thread: Spot putty sanding help

  1. #1
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    Spot putty sanding help

    Ok im using spot putty as I have hi filled, guide coated and wet sanded down all panels and the car and have came accross some pin holes to fill up as i want the paint to close as perfect now my question is i applied the spot putty which doesnt use hardner and now i need to sand it down have people wet sanded the putty or has to be dry sanded first than wet sanded and can you get away without re hi filling as im blocking it down so should still be even and putty inside the pin holes only the rest will be highfill once evened out.

  2. #2
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    Re: Spot putty sanding help

    hi buddy

    you mean a red putty that come in a tube.if you have finished off in 2-pack high build primer then you can apply spot putty but be carefull how much you put on as when you apply anything over a flatted finished primer you could end up with a dip in the primer as when you flat the stopper you flat the surround area of primer.what i sometimes do is use a coctail stick and mixe some primer that you have already used and drop a droplet into the pin hole,then when you take a block you can then block over area and it will only flat the slight pin hole lump and will flat the primer into the hole and not any of the surround primer,the last thing you want is a load of dips in paintwork when looking down side,if you paint in a 2-pack paint then you can also use the same method if any pinholes still there,pretty easy buddy.and save having to try and re prime it back up.

    if you have already applied the spot putty then make sure you make nice even strokes with the block both ways over the top of putty so it will hopefully evenly flat the putty down onto primer,use something like wet and dry 1200 and finish off in 1500 so you remove any scratches and if you think its too smooth just run a light grey scotchbrite over it with some prep and blend and it will scuff up surface and not scratch,

    ive finished mine in 1500 and then scuffed up shiny surface with greay scotch,this way the paint wont have any scratches to sink into and you have a good base to paint over and leave a lovley shinny paint job.

    hope this helps buddy and if you need any info let me know

    regards

  3. #3
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    Re: Spot putty sanding help

    yeah thats the stuff we get them in tubs instead of tubes but yeah i applied it already so going to go wet sanded it tomorrow hopefully goes all good will keep u updated thanks.

  4. #4
    Senior Member powerslave's Avatar
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    Re: Spot putty sanding help

    Another thing you might want to be careful of is that sometimes the red putty with bleed through your paint depending on the color. You have to make sure and throw a light coat of primer over your red putty before you paint. It may only be a small spot, but I've seen it bleed through. Also, I always always always use a sanding block of some kind, whether it's a paint stick or a sanding block, you never want to just fold the sandpaper over and spot sand the putty because it's possible to make a small divot in the primer that wouldnt be visible until you have your final paint applied.

    As far as wet or dry, I usually go wet because it will make your paper last a little longer. Sanding the putty without water usually gums up the paper almost immediately. Since you'll be applying a light coat of primer afterward anyway, I go with 400-600 wet over the putty, light coat of primer, guide coat, and finish with 600-800 wet.

  5. #5
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    Any one know how deep hole/gap you can fill with putty, trying to work out if I should use Bondo or not before the putty?

  6. #6
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    You shouldn't be filling anything larger than pinholes or sand scratches with the red putty that is not activated. If it's bigger, use a thin, activated spot filler instead. Bondo brand, as well as many others, make one that comes in a small plastic container that you squeeze out. The activator is typically white or blue instead of brown or red. It's thin, or runny so it spreads easy but dries hard just like typical body filler.

  7. #7
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    I was asked to sand/buff out some medium to heavy scratches in a Dune Buggy fiberglass body (yes, the old style dune buggy that fits on a VW chassis). I had first used some thin spot filler with activator to fill a few "nics' and wet sanded these fills (spot filler was colored the same red as the red sparkle of the dune buggy and nics were small). I am not sure what method to use for the medium scratches. I was thinking about wet sanding first with very, very light sand paper but now wonder if that would remove the gloss from the dune buggy body. I doubt even heavy compounding and buffing would remove the medium scratches (maybe the small ones).

    The body is not painted but rather fiber glass "finished" ... kind of like a boat with the colored gel coat with gloss finish and the color is the old style dune buggy red sparkle.

  8. #8
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    Everyone has opinions. Here's mine. I've been at this (building or restoring cars) all my life. Through that stuff in the trash. If you've already but it on, sand it off. If you are going base/clear, that uncatalyzed putty will suck the solvent out of your basecoat and trap it there and will slowly release the "tail solvents" for months after you have painted your car. If you are lucky, all that will happen is the dye (red, blue, whatever) will stain your finish. Worst case is the trapped solvent will eventually cause it to peel. That stuff was invented to go under lacquer back in the 60's and 70's. If you have a need, switch to the catalyzed equivalent like dolphin glaze, metal glaze, etc. My opinion, that's it, no more.

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