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Heads Up on a Finishing Process

Discussion in 'Luthier's Corner' started by LedBelli Bass, Apr 3, 2009.

  1. LedBelli Bass

    LedBelli Bass Fine, Handmade Custom Bass Guitars

    Dec 25, 2008
    Pasco, WA
    Hey all,

    Today I learned something new and interesting that anyone out there who's interested may wanna NOT try:

    I sealed a neck today with McFadden's Vinyl Sealer/Washcoat (which is nitro-lacquer friendly), let it dry, and then shot it with semi-gloss/satin poly finish.

    By the time the poly dried it looked like a cloudy day on that neck!

    It seems there may be an incompatibility issue here, so heads up on that one!
  2. jordan_frerichs


    Jan 20, 2008
    Then its a good thing I don't like poly!
  3. hbarcat

    hbarcat Supporting Member

    Aug 24, 2006
    Rochelle, Illinois
    Interesting. :atoz:

    I just shot a bass body this afternoon with some PPG Deltron clear over that very same McFadden's Vinyl Sealer/Washcoat.

    I hope I don't get an interesting surprise when I check on it tomorrow.
  4. LedBelli Bass

    LedBelli Bass Fine, Handmade Custom Bass Guitars

    Dec 25, 2008
    Pasco, WA
    Now this is even more interesting. Whatever this cloudy "residue" is, it rubs off with 000 steel wool, leaving a really nice satin finish . . . this is weird.

    Whatever is going on, it's a reaction of some kind with the sealer. Wherever I've used this poly on bare wood before it has never done this.
  5. 62bass


    Apr 3, 2005
    Could it be moisture in the air? I've had that happen in high humidity with very fast drying finishes if the work piece is cold.
  6. I hope this relates....I took some 0000 steel wool to the back of my MIJ Jazz Bass I just bought to smooth out a few minor nicks.

    If I got down pass the factory neck finish, what exactly would I put on the back of
    the neck to make it a satin finish? and how?

    Thanks (I'm a noob)
  7. T2W


    Feb 24, 2007
    Montreal, Canada.
    I think you may be on to something.. this happened to me a while ago when I put poly over some not-so-cured-oil. I had rubbed it off with wool just like Cleve said. It happened just this weekend again with Harley's bass. Ive never had a problem with bare wood either
  8. 62bass


    Apr 3, 2005
    Yeah, around here we get extreme humidity at times. Makes for interesting finishing. I try to keep the work warm and the finish at 70F or higher. When I work in my basement shop, I use a de-humidifier.

    I've used a vinyl sealer, not McFadden's though, and not had problems applying anything over it after it had thoroughly dried. The spray cans of poly seem to have a very fast drying solvent compared to the canned stuff. The fast evaporation cools the finish quickly and that can precipitate moisture in the air into the finish causing that cloudy look.
  9. powerbass

    powerbass Supporting Member

    Nov 2, 2006
    western MA
    it sounds like a moisture issue, it is called "blush" when you get the cloudy appearance on nitro finishes. dry and warm/not hot conditions is best for lacquers. if you have a spray gun you can add retarders to the finish which will allow the moisture to escape while drying. nice thing about nitro is you can scuff sand and reapply
  10. LedBelli Bass

    LedBelli Bass Fine, Handmade Custom Bass Guitars

    Dec 25, 2008
    Pasco, WA
    That's good to know you guys, thanks. In this case, fortunately, it worked out.
  11. gyancey


    Mar 25, 2002
    Austin, TX
    In general ya'll should be a little more specific when saying "poly". There's a HUGE difference between spray can polyurethane vs two part catalyzed polyurethane or even polyester for that matter, which some people refer to as "poly" and is completly different.

    Ledbeli, wild theories for the blush: 1) some of the flattening agents in your finish probably floated to the top 2) off-gassing from the sealer reacted with poly, creating a precipitant that floats.
  12. Your MIJ bass has a clear Polyurthane finish on the back of the neck. To go through the finish with 0000 steel wool, you would have to rub on it for a long, long time.
  13. Yeah, I know. I wanted to know what you would use once you did go through that finish or if you purposely wanted to get through all of that finish to finish it with oil.

    I used 0000 to smooth it out, but I have more finsih left.
    I'm happy with the results. I bought a 1988 MIJ Jazz Bass,
    used the steel wool and dropped in a Audere Preamp all ofr $550 total (plus $3 for the wool). :)

    Attached Files:

  14. Actually stripping the poly finish from the neck is a big project. Do you want to do just the back of the neck? The back of the headstock? The front of the headstock? Just trying to refinish the back of the neck presents problems. What do you not like about the present finish? Trying to finish one section in oil and another in poly is not a good idea.
  15. Hey LedBelli can we see some photos?

    Also what exact products did you use? I am interested in reproducing the effect.
  16. Really? I've seen other posts that had people saying they only did the back...I wouldn't know, that's why I'm asking.
  17. mslatter


    Apr 8, 2003
    Why'd you use the vinyl sealer under poly? Did you just have it handy, or were you shooting for a particular outcome?

    Shellac is considered a universal sealer, compatible with just about any consumer available finish. It's also very easy to apply well.
  18. 62bass


    Apr 3, 2005
    To finish it with oil successfully you'd have to get it down to bare wood--which is a lot of work sanding. Wouldn't trust myself using a heat gun on a neck. Chemical strippers won't remove the factory finish. So it's sanding. But, if you sand the existing finish smooth without going to bare would you could refinish it with any of several hard drying finishes, like wipe on poly, spray on poly, clear acrylic spray from a spray can, etc. As long as it's a finish that dries hard and the existing surface is properly prepped there should be little problems.

    The oil finishes, like tung oil,True oil, Danish oil, etc. work best on bare wood where they soak into the wood and aren't built up to a thick film. They're too soft even when fully cured to stand up to much wear when built up to a thick film.

    Sounds like you did it right.
  19. gyancey


    Mar 25, 2002
    Austin, TX
    A well-sharpened cabinet scraper will take off a finish much, much faster than sanding and without the dust (but lots of neat curls)
  20. powerbass

    powerbass Supporting Member

    Nov 2, 2006
    western MA

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