Wet sanding woes

Discussion in 'Archived Threads 2001-2004' started by Robin Smith, Jun 26, 2002.

  1. Robin Smith

    Robin Smith Stunt Coordinator

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    Hi,

    I am using glossy black spray paint and wet sanding between every two coats. I am using 600 grit sandpaper. The problem is, when I finish the coats of paint they look slightly stippled. I wet sand and it knocks the stipple down achieving the smooth finish I desire but the paint now looks dull. What am I doing wrong.

    The finish almost has a slightly grey tinge to it. I have never wet sanded before so its all new to me. I have spray lacquer to finish it with. SHould I start alternating between lacquer and black paint to get a shinier finish or just start layering on the lacquer and sanding between coats? Any help would be appreciated.

    Thanks


    Robin Smith
     
  2. Patrick Sun

    Patrick Sun Moderator
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    You should only use lacquer on lacquer for the best results.
     
  3. Will Pomeroy

    Will Pomeroy Stunt Coordinator

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    Also, consider using a WAY finer grit sand paper (like 2000), and make sure that there is absolutley no dust, that'll give you that grayness...
     
  4. Patrick Sun

    Patrick Sun Moderator
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    You are using "wet" sandpaper, right? You can get it at auto parts stores, and you do need at least 1500 grit and higher for that mirror-like shine.
     
  5. Robin Smith

    Robin Smith Stunt Coordinator

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    I'm not really going for the piano finish as it is way too much work and my spray skills aren't good enough. I just want to get a smooth and reasonably bump free glossy finish.

    The paper I am using is a wet/dry sandpaper from home depot. It is 600 grit. I soak it for 15 minutes before sanding and use a decent amount of water as I go. I am sanding in a circular motion using a rubber sanding pad.

    Pat, are you saying that I should NOT alternate clear lacquer and black paint or are you saying the lacquer wont work over my paint. I saw your painful documentation of what happened to you and tried the lacquer over my paint on a scrap and it seemed fine, no weird peeling or anything.

    Both the gloss paint and the clear lacquer are the same brand of paint and they were next to each other on the shelf. The guy in HD told me it was compatible. Now, I know the HD guys are not the be-all and end-all of expert advice, but he seems to have steered me straight as the lacquer did nothing to the black glossy paint underneath on my test piece. The black paint does not explicitly say "lacquer" on the can though.

    Thanks

    Robin
     
  6. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    As has been mentioned, move to some higher grit "wet" paper- try auto supply stores if hardware store doesn't have it.Try about 1200 after the next coat, then 2500 then 4,000. The higher the grit, the less greying. Also, pick up a small can of mineral spirits and wipe with a paper towell after the water has driedbefore spraying the next coat. This will remove the fine dust particles that are contributing to the greyness.
     
  7. Fred Seger

    Fred Seger Stunt Coordinator

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    perhaps you'd be happy with just finishing it with a high gloss transparent finish/sealer.
     
  8. David A. Frattaroli

    David A. Frattaroli Stunt Coordinator

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    To minimize the effort, start with 400 then move to 600. I would also suggest finishing at a much higher grit like 1200 or 1500 but only for the final coat. When you move to a higher grit the object is to remove all the scratch marks from the previous grit. This is how you know you're done with the current grit.

    The gray tint is ok. That's what black looks like when you sand it. In fact, you don't need to spray gloss black during the sanding stages since you're sanding it. You're final gloss coat, colored or clear should be well, glossy.

    The finishing stages are the stages that will restore the luster and shine. Don't expect to finish sanding, even with a grit as high as 1500 and see a piano finish. You need to buff the finish with a compound and then a wax and then a glaze. It's a lot of work but you'd be surprised how easy it is. The reason most folks don't do it isn't because it's difficult but because it's tedious.

    Good luck.

    Dave
     
  9. Dan Wesnor

    Dan Wesnor Second Unit

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    Get a new can of spray paint. Some cans just don't spray very well, especially if their almost empty or they've been sitting around a while.

    Be sure and follow the directions on the can, especially with regard to spray distance.

    Did you properly sand and prime the surface first? Most paints will accent any imperfections.

    Make sure to let it dry in a dust-free environment.

    If it's that $1.97 stuff from HD, try the $3 or $4 stuff. If it's going on stippled, high-grit sandpaper won't fix it.
     
  10. Patrick Sun

    Patrick Sun Moderator
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    I'd stay with clear lacquer and black lacquer, and perhaps alternate the layers.
     
  11. Robin Smith

    Robin Smith Stunt Coordinator

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    Cool, thanks for all the replies!

    Pat, its too late for the black lacquer, clear lacquer deal as I already have two cans of the glossy black paint on. It was not the cheapest paint but not the most expensive.

    The brand name is: Painter's Touch by Rust-oleum

    Here is what I did:
    I started with a can of grey Painter's Touch primer. Then two cans of glossy black.

    1. Sprayed a coat, waited an hour, sprayed another coat.
    2. Left it for 24 hours
    3. Wet sanded with 600 grit and dried it off with a cloth
    4. Repeat

    I did the above steps two times with the primer and four or five times with the black.

    The black does not have an even shine across the surface, some parts seem "wetter" looking than others. The whole thing has a greyish tinge as mentioned above.

    I'll get some mineral spirits and use that to wipe off the top and I'll try and get a finer grit paper for the lacquer coats. Thanks for the idea Brian. Won't the mineral spirits harm the paint if I use too much, isn't that what paint thinner is?

    Also, can I sand with a palm sander or should I stick with the hand held block in a circular motion?

    Thanks


    Robin
     
  12. Joe Tilley

    Joe Tilley Supporting Actor

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    Robin, when sanding you should use a cross hatch motion (X) this will make it easier to polish & give you a more uniform surface. Like others have said start with a much finer paper like 1000 or 1200 & work from there,also add just a couple of drops of dish soap to your water this will actually help to soften up the paper some & will keep the paper from loading up with dust.
     
  13. Patrick Sun

    Patrick Sun Moderator
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    Well, go buy some black lacquer paint! See if that helps, it's only $4-$5 for a can.
     
  14. Robin Smith

    Robin Smith Stunt Coordinator

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    Should I just spray it on over top of all the layers I have done so far or should I sand down and start again. Can paint be too thick?

    Robin
     
  15. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    1) The mineral sprits should not affect dried laquer. Not sure about the painter's touch black your using, but just rub hard on an inconspicous area to be sure it won't soften the paint.

    2) If your major prpblem at this stage is the greying after sanding, do not remove to restart. You can continue to build from the base you have. However, if there are a lot of surface inperfections, you may want to take a step backwards a little and sand aggresively with 400 or so grit to try to get level, then repaint and sand with progressively finer grit.
     
  16. Robin Smith

    Robin Smith Stunt Coordinator

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    Okay, so I have finished the finish on my sub. Not quite satisfied with the reslts, but it will do. I have realized I am not cut out for spray paint as I can;t seem to get a consistent finish.

    Thanks for all the tips in this thread. I have a couple more questions.

    I have done two layers of lacquer. I sanded with 1500 grit in between the layers. When the final coat is dry (tomorrow or Monday could be sub construction day!) should I give it a final sanding with the 1500 grit? Or is that only for "between" layers.

    Also, I plan on buffing/polishing the finish somewhat and am wondering exactly what tools I should use.

    David, you mentioned: compound and then a wax and then a glaze
    What exactly should I use for all of these (both the product and the application methodology.

    Are we talking car wax or furniture polish? Any brand recommendations and/or tips.

    Thanks

    Robin

    I can't wait to finally hear my sub after all this effort! Its my first DIY audio project.
     
  17. Joe Tilley

    Joe Tilley Supporting Actor

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    Robin, if you can get or have a electric buffer you would use it with a wool buffing pad & compound. Some of the better stuff I've used is Meguries Diamond cut compound,than finish it up with a foam pad & some 3M perfect-it 3 polish for a high shine,you shouldn't need anything else.
    I don't know how far some of the guys around here go with this kind of stuff Im just going by what I know (I've painted cars for thirteen years)& I can honestly tell I can make the side of a car look like a mirror.

    And by the way if you have sanded down to 1500 & plan on using a buffer & compound it will work just fine. If however you cant get a buffer take it down to 2000 & hand rub it with compound & a terry cloth towel,it takes a little more work but you can still get a nice finish.
     
  18. Robin Smith

    Robin Smith Stunt Coordinator

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    Thanks Joe,

    What I am not sure about is whether I should do a final sanding *after* the last spray coat

    i.e. Sand, Spray Final Coat, Sand, Buff/Polish

    or

    i.e. Sand, Spray Final Coat, Buff/Polish

    If I do a sanding after the final spray of lacquer, will I be able to buff the sanded surface to a better finish than unsanded?

    Thanks

    Robin
     
  19. Joe Tilley

    Joe Tilley Supporting Actor

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    Robin, If you wont the smoothest finish possable with a mirror like shine you will need to sand & buff it after your final coat of paint. You can just buff the last coat without sanding it & get a pretty good shine,but any imperfections that are there will stay there (eq orange peel,or any dirt that may have got in the paint)
    Good luck[​IMG]
     
  20. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    do not sand the last coat. Just buff. And give it at least a few days to cure before attacking with the polishing compound.
     

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