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"Finishing" a finish job

Discussion in 'Hardware, Setup & Repair [BG]' started by Jontom, Jun 12, 2002.

  1. Jontom


    Mar 11, 2002
    New York
    I have been putting a coat a day of rub-on polyurethane(for the past two weeks) on a Warmoth J-bass that I initially stained(3 coats). I've been using lint-free cloths to apply the poly, although I still seem to get flecks of dust in the coats. I use a 3M Superfine sanding foam in between coats to get the specks out. However,when I reach the final coat how do get the job "finished"? I have a buffing pad I can attach to a drill and some Meguiars polish. Should I sand out the specks on the final coat and then polish, or should I get a rubbing compound of some sort?
  2. most likely, it would be a final wet sanding with 600 then 1000 grit wet/dry paper, then buff with the proper polish or compound. the poly should (i hope) have some sort of instruction about the proper product to use. the only thing to worry about is compatability. it would suck to cause any kind of clouding to the finish after all that work.
  3. Don't worry too much about the flecks of lint in the finish. You would get these in most any situation, no matter how careful you are. Buzz has it right about how to "finish" but I would add that you might want to go to even finer grits - 1200 and up. What you want to end up with is a poly finish that is nearly a gloss before you begin polishing. Also beware that poly doesn't polish as easily as nitro finishes. Poly is "tougher" but not as hard as nitro. I is easy to get it a little too hot so be careful.

    By the way, if you can't find the 1200 and up grits locally, you should try a brown paper bag from the grocery store. These are used by fine wood finishers as a 1200 grit paper and it works pretty good.
  4. Jontom


    Mar 11, 2002
    New York
    I used a 1500 grit paper and sanded the whole thing, now I have sand marks. I put another coat of poly on. The effect I'm trying to get is to see my reflection in the bass. So far, all I see is lots of sand marks, fuzz, and mistakes in the top coat. How do I get rid of that and have a highly-polished "finished" professional looking bass?
  5. are you wet sanding? because you must have water as a lubricant. with 1500 paper and water you should end up with a super smooth cloudy finish. then retore the high gloss with a buffer and the proper liquid polish.
  6. Jontom


    Mar 11, 2002
    New York
    Fretbuzz...What would you recommend as a good polish over polyurethane?(To be used with a buffer).
  7. i would try using (buffing) some of the liquid polishing compunds that are available at most auto parts stores. most are safe for clear finishes, then buff in liquid polish/wax. 3M makes a whole line of products to choose from. i have never investigated any other suppliers. BUT as i said before, make sure its compatible with the poly you have used. -let me know how its coming, peace.
  8. Jontom


    Mar 11, 2002
    New York
    I talked with a local guitar tech, and he suggests Meguiars in the following order: 2,9,7. The thing is the wipe-on poly (Minwax) has no suggestions as what to use to get the job "done". It says "after final coat,allow to dry overnight before normal use". THANKS!
  9. bass players are NOT normal. you better not try to play it, god knows what might happen!! -peace.
  10. sleazylenny


    Jun 20, 2002
    Mpls, MN
    If you have sanding marks, imperfections and scratches, that means you didn't spend enough time with the heavier sandpapers. You may have to go back to the rough and start again for the "mirror finish." Usually when the imperfections show up during the finer grades, it's because the heavy grades weren't complete. Another problem can be sanding before the coat has set, which smears it.
    I don't think you'll get the effect you're looking for with wipe on poly. Even the glossy stuff isn't as shiny as most factory fininshes. Do you know anyone in the auto painting biz? You might find someone to shoot a clear coat finish on it while they're doing a car. But beware the compatibility issues. I've seen some finishes react poorly with others.
  11. Jontom


    Mar 11, 2002
    New York
    All I know is that when I would sand with the 1500(wet w/lemon oil), I would keep ending up with "scuff" marks where I would sand out the imperfections. I would try to polish out the scuffs, but they weren't going anywhere. Finally I gave up, did a final swipe over with poly and tried to keep it as lint-free,cat-hair free,and even as I covered up the scuff marks. How long do you suggest I let it cure before doing final sanding/polishing?
  12. pkr2


    Apr 28, 2000
    coastal N.C.

    The first coats of poly serve as a sealer. It sounds like you are sanding through the sealer into bare wood.

    You will always have a certain amount of fuzz when you sand bare wood. The finer the sandpaper grit that you use, the less fuzz you end up with.

    The idea is to have enough sealer applied that you dont get into bare wood.

    Using a liquid to lube the sandpaper is counter productive on bare wood since the liquid will keep raising the grain as you sand. Wet sand only a well sealed surface and be very careful not to sand through the sealer coat(s).

    Ideally, a scraper will give a MUCH smoother surface on bare wood than sandpaper. The down side to a scraper is that a certain amount of skill is involved to get a glass smooth surface. Not real difficult but does require some practice.

    I'm not sure that I would be using lemon oil as a lube because any kind of oil will leave an oily residue that may not be compatible with the final coat.

    Plain water would be my choice since it evaporates away and leaves no residue.

    My suggestion would be to clean the surface with naptha to remove all the lemon oil. Resand the surface using a brown paper bag in place of the sand paper.

    Apply two or three coats of thinned poly with a foam brush and finish sand with the finest grade of wet/dry sandpaper lubed with water with just a tiny amount of dishwashing liquid added. Clean the surface with only water and buff with the brown paper (dry). Apply the polish of your choice to finish up.

    Something you may want to keep in mind: The glossier the finish that you choose, the more critical the prep work becomes. A satin finish is much more forgiving.

    Another tip is to use a tack rag after each sanding and just before putting the poly coats on. That will remove all traces of dust.

    I hope this helps. You have my sympathy since the first finish job i did produced a lot of the same problems that you are having.

    Patience is the key.

  13. Jontom


    Mar 11, 2002
    New York
    pkr2- Thanks for the good ideas! I'm not sanding any bare wood, I'm going very lightly in the areas that have imperfections only. I like the idea of thinning the poly. I could see maybe thinning it to the point where it dries shortly after application, which would lessen the chance of stray dust getting in there.

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