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Polyurethane finishing.

Discussion in 'Luthier's Corner' started by Aka Nameless, Jun 8, 2007.


  1. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    I've decided to finish my First Bass Build with Minwax Wipe-On Polyurethane "I'll use the Target Coating stuff next time Wilser".

    Should I use this stuff from first to last coat? Or should I apply a pore filler before I apply this stuff? I was told that you could thin out the poly with mineral spirits and use it as a pore filler, then apply a good 10 coats of undiluted Polyurethane as the clear/protective coats.

    Anyone see a problem with going this way?

    Any advice would be great, this is my first finishing job.
     
  2. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Also, when applying a Poly finish with a foam brush, should I put a coat on the top, let dry, then a coat on the back, let dry, then sand, rinse, and repeat?
     
  3. You don't have to answer to me! :D

    I've used this stuff before and though its nice, its kind of difficult to build up to achieve a gloss finish (you haven't mentioned what you want to achieve).

    As far as using it as a filler, you need to THICKEN itN not THIN it. You can use it as a sealer by thinning it like you described, not a filler.

    I applied it thinly and aggressively with a rag. Brushes (foam or other wise) I wouldn't recomment because this stuff needs to be applied thin to ensure proper cure.

    PS, this product is oil based.
     
  4. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Ya, I want a high gloss finish, like a glass-like epoxy fretless fingerboard finish, all over the guitar.

    I already purchased the minwax wipe-on poly and foam brushes =-/ So you suggest using a microfiber rag? When you used this stuff, what did you use as a pore filler? The walnut I used isn't that open grained, but there are a couple very tiny "pinhead size" knot holes in it that should be filled.

    Is there a better brand that Home Depot would sell that would be better than the Minwax Poly? I saw that they had some Minwax Waterbased Poly, it wasn't called wipe on, but the process to apply it was pretty much the same.

    What is the downside of oil based?

    Thanks for the info, sorry that i'm so full of questions. =)
     
  5. First, I do not claim to be a poly finishing expert! :D

    I used it on maple, so no pore filler was needed. Walnut is open grained. you will realize once you start applying the finish. It's not as readily aparent as when you sand the first couple of coats and see all the shiny spots remaining where the sandpaper isn't touching the finish in the pores. You CAN use wipe on, just requires a LOT of coats and patience.

    I think you're better off using their canned spray poly. It's easier to build up and apply.

    Happy finishing!

     
  6. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Cool, think i'm gonna go return this wipe on for some spray on poly. Using the spray on Poly will be ok from pore filling to final coat, correct?
     
  7. will still require many coats and sanding in between. But spray cures faster.

    Do not expect your first finish to come out perfect. This is something that can only be learned by doing. And though you can get pretty well documented beforehand, it's mostly by trial and error that you can achieve what you have in your head.
     
  8. tjclem

    tjclem Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    I normaly use the wipe on then the spray with my spalted basses. The idea of using the wipe on first then lay on a coat of brush on to level the surface then sanding and switching to spray sounds interesting though.....t
     
  9. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    I know it probably won't come out perfect, but perfect is a good thing to shoot for.

    So, when finishing, I spray it on then rub it in with a brush right? The can says, spray on and it self levels "which I highly doubt".
     
  10. DigthemLows

    DigthemLows

    Oct 10, 2003
    Sacramento CA
    I used the spray on for my fretboard and I didn't wipe it at all. A couple of quick passes of some Steel wool in between coats (after it dried for a while) and it turned out pretty good. Not perfect, but I'm happy with it!
     
  11. Like Digthemlows said, you don't rub it in. In spray form it's designed to be sprayed and then wait for it to dry before sanding or steel wooling and then on to the other coats, and repeat.
     
  12. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Great, thanks guys. Once i'm happy with the final sanding... i'll get to spraying it down.

    When you know it's your last chance to fix any flaws in the sanding, you notice microscopic flaws.. everywhere.
     
  13. 202dy

    202dy Supporting Member

    Sep 26, 2006
    Minwax Wipeon Poly used as a pore filler is actually a good idea. Apply one or two coats to get a decent seal against the wood. Apply the next few coats with 600 grit wet or dry paper. Create a slurry on the surface. Let it rest for until it just starts to tack then wipe off at an angle to the grain. Two or three days of this will create a good, dark filler. Then finish with spray poly.

    Or you could use standard pore filler and finish with poly. The filling process will be done in a day or two.
     
  14. DigthemLows

    DigthemLows

    Oct 10, 2003
    Sacramento CA
    and there's nothing wrong with keeping the can 12 to 14 inches away at least while you spray........20 thin coats is safer than 3 thick ones.............
     
  15. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Ok, I ended up with the spray, and i've sprayed 3 thin coats an hour apart with no sanding in between, it seems to have filled the pores nicely. Now I want to sand back the high spots, so the finish will be perectly even.

    How long should I wait after spraying a coat, before I sand it smooth and apply the next coat? The can says to apply coats within 2 hours of eachother, and if you wait more than 2 hours, you should wait 72 hours then sand and recoat. So should I sand it even and apply the next coat before the 2 hour mark, even if it is a little tacky feeling still? Or wait the 72 hours between coats?

    Man, I am full of questions.

    Hopefully someone can give me some advice.

    Thanks.
     
  16. Joth

    Joth

    Apr 22, 2007
    Be very patient here, give it at least two days to do a sanding levelling, the reason is that if its still soft at all the sanded particles will gum up and roll on each other, it wont shear cleanly from the sandpaper, also it needs to dry down and stop shrinking, ive done two guitars and a few neck touchups with the wipe on product, but I see the threads strayed over to the spray which i havent used, but the idea applies to all finishes, you cant rush level sanding, or final prebuff sanding either.
     
  17. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    Ok, an update on the bass, and a few questions.

    I have sprayed a total of 13 coats, with a light sanding with 320 grit in between so the next coat has something to stick to. After the 13th coat I decided that the finish is thick enough, so the bass has been curing since last thursday (week and 3 days). The finish feels hard enough to do the final buffing/etc, my fingernail can only dent the finish if I apply a LOT of pressure.

    Now for the questions..

    There is a little bit of orange peel on the final coat, and i'm not sure how coarse of sandpaper I should start with to go from removing orange peel to final buffing. I have all the regular sandpaper up to 600 grit wet/dry, and I also have 000 and 0000 steel wool. I'm thinking 320 grit to get rid of the orange peel, then 400, then 600, but the next finest I have after 600 wet/dry paper is the 000 steel wool. Is that too big of a jump? Should I go out and try to find some emory cloth to use instead of steel wool?

    Any help would be great.

    A little walkthrough of how you guys do your final sanding/buffing to get a clear poly finish, would make my day.

    Thanks in advance.
     
  18. tjclem

    tjclem Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    Go to a place that sells auto body supplies and paints. not a "parts store" they have much finer grits.t
     
  19. Aka Nameless

    Aka Nameless

    Oct 24, 2006
    I guess the main question I have is, once everything is nice and sanded, what should I use to get the final gloss polish? 0000 steel wool and a polishing compound? or maybe 0000 steel wool with a wax? The back of the steel wood package says for final coat, polish it with 0000 steel wool and wax. But what kind of wax? should I be shopping at autozone for the last step?

    Thanks in advance.
     
  20. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Mar 6, 2021

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