Whats the Proper way to wetsand?

Discussion in 'Luthier's Corner' started by lovebrigade, Jul 18, 2008.

  1. lovebrigade


    Aug 1, 2007
    Im on the paint stage of my first bass project but am not sure how to wetsand. I looked it up online and most of the results are for cars and some say not to use water, and use other liquids and some say to use water and some say you dont even need a liquid? Whats the best way or best liquid to wetsand with when dealing with paint on wood?

    Thanks A lot, LB
  2. zac2944


    Dec 28, 2004
    Rochester, NY
    IME, I use plenty of water to keep the paper from getting clogged, and use a straight sanding motion in alternating directions. I do it by hand with a block. I'm no finishing expert though. I'm sure someone with more experience will chime in soon.
  3. tjclem

    tjclem Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    The few times I have done it I add just a drop of dishwashing soap to the water. But I am sure somebody with more knowlege will post.....t
  4. 62bass


    Apr 3, 2005
    I've used both mineral oil thinned with Varsol and water. I prefer water only because it's easier to clean up. They both seem to cut as well.

    Remember to wash off all the slurry when changing to a finer grit and also remember to change the water at the same time. You don't want any pieces of the coarser sandpaper marking up your finish.

    I like to put a drop of dish soap in the water. It seems to help. Also soak the sandpaper for a few minutes before beginning to sand.
  5. scottyd

    scottyd Commercial User

    Nov 17, 2006
    Waco Tx
    Builder/owner Redeemer Basses
    I use a little water with a couple drops of soap in it. If you are using conventional wet/dry paper let it soak in the water for a while before you use it. That'll soften up the edges and give the paper better flexibility.

    If you have any spots on the bass that are not sealed with finish very well try to not let water in those areas. It does not take a lot of water to sand just enough to keep the paper lubed up and to keep the sanding residue wet. I like to dry out the cavities as I go.

    When you sand you should use a crosshatch pattern to keep from sanding ridges in the finish. Not doing so will cause low spots and ripples which can be seen from angles. The crosshatch is simple but kind of hard to explain. Basically you just don't want to sand in the same parallel direction too many strokes. I use a pattern like this |||| //// \\\\

    Good luck!:D
  6. ewimsatt


    Jul 1, 2008
    Nashville, TN
    Pickup Maker, Luthier, and Repairman, Wimsatt Instruments
    I put the sandpaper i plan on using in a tupperware contain with water in it. A few minutes later, I pull out a sheet out and wrap it around the bottom of my sanding block. I don't add any water other than what stuck to it when I pulled it out of the bath. I sand finishes in a circular motion. I found that sanding in circles keeps me from unevenly sanding down teh finish before buffing.
  7. praisegig

    praisegig Gold Supporting Member

    Jul 7, 2008
    Stephenville, TX
    I'll use mineral oil with my wet/dry papers, starting at 800 up thru 2000 grit. I wrap my paper around a red or white rubber eraser used as a sanding block. When I change to the next grit, I will wipe down the body with naptha to remove the oil and sanding slurry from the grit before. I don't start on the sides until I get to 1500 grit. My last coat of nitro is a 50/50% mix of nitro and thinner, which usually leaves me with little or no orange peel. Others will use naptha or paint thinners as a lubricate for wet sanding, but water or oil doesn't smell and easier on the hands.

    I have used water/ soap mix, but only if I plug all the drilled holes with plumber's putty. This will keep the water out and not make the wood swell and crack the nitro.

    Sometimes I will use pumice and rottenstone or 3M compounds for my polishing stages.
  8. What specifically are you painting with, and I assume that you've already laid down your paint and are now at the point of smoothing out your orange peel? If that's the case, first make sure you follow all recommendations to ensure that the paint has fully cured. A week is usually fine, but it depends on what you used.

    Keep in mind that all the water is used for is to wash away the sanding slurry and to keep your paper clean, so it can do its job. The drop of dish soap also helps to make the water more 'slippery' if that makes any sense. The wood should be fully sealed out by the finish so the water shouldn't hurt it.

    Also you don't want to sand with just your fingers if you can help it. Doing so can leave grooves in the finish, from not sanding with a perfectly even surface. You can use just about anything as a block though; there are alot of foam or rubber sanding blocks made specifically for doing this, and you should be able to find them at any auto refinishing store. I use a simple flat rubber block/squeegee myself, about 4 inches square.

    Also remember to dry your work once in a while to see how it's coming along. If there's little shiny spots, those are the low spots below the orange peel, and it means you haven't gone far enough yet, so keep going. Once the dried surface looks perfectly even and smooth with a completely matte or flat finish, then you can move on to the next grit.
  9. Stu L.

    Stu L.

    Nov 27, 2001
    Corsicana, Texas
    Hey Lon, welcome to TB! Now I can get info from you here as well as the RR! :D
  10. praisegig

    praisegig Gold Supporting Member

    Jul 7, 2008
    Stephenville, TX
    Thanks for the welcome, maybe I can help at some point. Finishing is fun and therapeutic, keeps this 'ole brain busy.
  11. powerbass


    Nov 2, 2006
    western MA
    i use water and a little Murphy's Oil Soap which is very slippery. i use either solid felt blocks or glue thick felt (3/8") to a wooden block. solid wood blocks are too hard i think for rubbing out.
  12. praisegig

    praisegig Gold Supporting Member

    Jul 7, 2008
    Stephenville, TX
    Yeah, felt blocks are nice for wet sanding, and rubbing out if I'm use pumice/rottonstone and baby/mineral oil. For heavy orange peel I have piece of 2x4 with cork glued to the bottom. It is cut to fit my hand nicely, and use it for dry sanding and leveling. I use the eraser for wet sanding up to 2000 and the 3M pad for the sides and contours.
  13. Definitely use a hard block for levelling, and definitely sand in a circular motion on flat surfaces. You don't need too much pressure either.

    And definitely clean off and change the water between grits.
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