How to tell: oil or poly finish?

Discussion in 'Luthier's Corner' started by Spfairchild, Mar 27, 2014.


  1. Spfairchild

    Spfairchild Supporting Member

    Joined:
    Oct 23, 2005
    Location:
    Seattle
    Hello all,

    I have a quick question for you, after spending quite a while googling around and not finding any definitive answers.

    I've just bought a used Spector bass and I'm trying to discern whether the finish on it is the oil based finish they used to use or a poly finish. My question is: is there a definitive way to tell which finish an instrument has - a test of some sort?

    The bass was made in January of 2008, right at the cusp of the period where the company switched from oil to poly finishes. I contacted Spector but they couldn't tell me outright which finish would have been used. Basically, I want to know so that I know whether I should be maintaining the oil finish with wax as I do with my Warwick, or not worrying about it at all as with my other poly finished instruments. But I am kind of hoping it's oil so that I can repair some surface imperfections as well, then re-oil/wax.

    So, is there a way to know? Thanks ahead of time!
     
  2. Spfairchild

    Spfairchild Supporting Member

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    Oct 23, 2005
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    Seattle
    I wonder whether this is a dumb question, or if it's that nobody knows if there is a surefire way to tell.
     
  3. Jazzdogg

    Jazzdogg Less barking, more wagging! Supporting Member

    Joined:
    Jul 29, 2006
    Location:
    San Diego, CA
    So-called oil finishes are often thinned varnish aka wiping varnish. These finishes typically provide more moisture and abrasion resistance than plain oil finishes, but less than full-bodied oil-based varnishes.

    Unfortunately, it can be difficult to tell the difference between these finishes, especially when freshly applied. In practice, what really matters to most people is the sheen level (how shiny the finish is), and how well the finish wears. My experience is that oil finishes provide the least moisture and abrasion resistance, with oil-based wiping varnishes, full-strength varnishes, and catalyzed varnishes each providing progressively more "toughness."
     
  4. Spfairchild

    Spfairchild Supporting Member

    Joined:
    Oct 23, 2005
    Location:
    Seattle
    Thanks for the info! Basically though, I'm trying to discern whether or not the instrument in question has a poly finish. If it doesn't, I know it's some type of oil, so I can do some minor refinishing and repairs if needed and will be able to repair the finish in that are with more oil/wax. The two options for this model were polyurethane or oil finish, so I'm trying to figure out if it's the oil finish that Spector used to use, that they also suggest waxing from time to time, so I know if I should be doing that and can also sand out some fine scratches in the wood.
     
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  6. Stealth Fighter

    Stealth Fighter

    Joined:
    Apr 14, 2013
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    Eastern North Carolina, USA
    What exactly do you mean by, "oil based finish they used to use"? Until you asked the question, I would have thought the answer would be obvious. Now, I'm not so sure. I would think of poly finish as a "plasticized" film lying on top of the wood, while the "oil" finish would have a more "woody" feel, since it penetrates the wood. However, that is just my guess. I, too, am awaiting an answer from the experts.
     
  7. Spfairchild

    Spfairchild Supporting Member

    Joined:
    Oct 23, 2005
    Location:
    Seattle
    Hi Stealth,
    I ordinarily think of Poly as a little plasticized too, but the thinly-applied satin and matte poly finish variations have been known to get a little glossy when they're worn, and this bass is 6 years old. It does have a bit of a sheen to it, especially on the back, which is mahogany. Quilted maple front. All maple neck, pau ferro board. The pau ferro is unfinished for sure, but I've read it's one of the fretboard woods that has enough essential oils to not require finishing.

    It's hard to tell! I do have a poly finish bass, and this one doesn't necessarily feel like that one, but it also doesn't really feel oily - if it is an oil finish, it may not have been kept up since the bass rolled off the line. If I had to bet, I would bet it's an oil finish, but that just brings me back to my initial question of seeing if anyone knows a way to be sure - last thing I wanna do is sand through a poly finish to repair some scratches and dings and then have it look or feel weird when I try to go back over that area with oil!

    Or, would that be weird at all? Maybe I'm concerned about nothing! I've just read time after time that either you can't really repair a polyurethane finish or it's very difficult. I've enjoyed having Warwicks and other basses that I can take some fine grade sandpaper to to smooth things out when need be, then re-oil and wax, in their case. Maybe I can do this no matter what the finish is, and it's not horrible? Just doesn't seem right though...
     
  8. Stealth Fighter

    Stealth Fighter

    Joined:
    Apr 14, 2013
    Location:
    Eastern North Carolina, USA
    I wish I could be of more help, but I'm guessing that if you can't tell if it is poly, it probably isn't, or at least, it is very thin poly. Got any pics?
     
  9. Spfairchild

    Spfairchild Supporting Member

    Joined:
    Oct 23, 2005
    Location:
    Seattle
    I do!
    It looks a little shinier in some of these than it actually looks in person, BTW.

    [​IMG]

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  10. Stealth Fighter

    Stealth Fighter

    Joined:
    Apr 14, 2013
    Location:
    Eastern North Carolina, USA
    Nice bass! My guess is not poly. Maybe someone more knowledgeable will chime in.

    Edit: Somehow I missed Jazzdog's post #3. IMO that's your answer.
     
  11. Hopkins

    Hopkins Supporting Member

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    Nov 17, 2010
    Location:
    Houston Tx
    Can't really tell from the pictures. Can you see the pores in the wood? If so its probably an oil finish, if the pores are completely sealed then its probably a satin poly. My best guess from looking at the end grain is that it is a satin poly, but that is just a guess.
     
  12. Spfairchild

    Spfairchild Supporting Member

    Joined:
    Oct 23, 2005
    Location:
    Seattle
    Well, the need to know if there is some kind of a test is now moot - see below; oil finish! I already had seen the evidence of a dripping oil stain when I took the pickups out, but when I took the bridge off, all doubt was erased. Good to know! I spent the next couple hours completely disassembling and waxing the bass. I always feel like I don't really know an instrument well or have a connection with it until I've taken it apart and/or modified something on it ;)

    [​IMG]
     

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