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Need details on TruOil + poly finish

Discussion in 'Luthier's Corner' started by Frank Martin, Nov 11, 2005.


  1. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Hello again!

    I've searched the threads, but can't seem to find some important details. Most are concerning sanding grit.

    I've at last received TruOil. I may have access to a spray gun this weekend

    So, the course of applying a TruOil and polyurethane finish, if I'm not mistaken:
    • Sand the wood to smooth and remove scratches (to what grit should I sand? 600? 1000? Else?)
    • Rid the surface of sanding dust (another problem - very fine dust seems stuck in the pores... how to get rid of them?)
    • Pore filling (optional), leaving it to dry, then sanding to level the surface
    • Apply and spread oil on the wood
    • Allow it to dry for at least 2 hours
    • Buff lightly with 00 steel wool (I haven't seen steel wool around - what should I use instead?)
    • Repeat the two previous steps a few times
    • Spray or wipe on polyurethane - spray light/medium coats; then allow it to cure fully
    • Sand/buff with steel wool
    • Repeat these a few times, as well.
    I need some pointers about spray finishing polyurethane with a spray gun, as well, as I couldn't find much about it. Any special things I should look out for besides applying light/medium coats, letting it cure and then buffing with steel wool?
    Also, what should I get that dries/cures faster? (I'd like to finish it over the next two weekends, before the weather turns too bad for outside work)

    Many thanks!
     
  2. JSPguitars

    JSPguitars

    Jan 12, 2004
    Grass Valley
    I've never sprayed, so I can't help you there.

    However, steel wool SHOULD be available near you, unless you're from mars. It's pretty common stuff. I buy the OOOO kind at Orchard Supply. I would think any hardware store would have it, or at least be able to order it for you.
     
  3. jeffhigh

    jeffhigh

    May 16, 2005
    Have not used truoil myself, but I believe it is a finish all by itself, not an undercoat for polyurethane. I would be concerned that the poly would not adhere well to the oil finish.
    Jeff
     
  4. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Thanks for the replies.

    I've tried finding steel wool at a few hardware stores, but without luck. There's sandpaper, but the things closest to steel wool that I found were household/kitchen abrasives, and they were chemically treated, which could be bad for the finish, or so I presume.

    TruOil is indeed a finish by itself, but many on this forum have reported using this combination with great success.
     
  5. they say preparing the surface to 220 before applying finishes is enough. I don't know if it's the paper I use (norton 3x) or what, but my 220 still looks to rough. I go to 320 or 400 for wood preparation.

    For removing the dust I use a tack cloth. Now, these leave a somewhat sticky residue that should be removed, I use acetone for that. This will leave your pores quite clean.

    It's 0000 steel wool that's used for buffing, the lesser '0's are too coarse to leave a good finish. Even 0000 will leave a satin finish, not glossy at all. Steel wool can be had at those places that polish granite floors. If you want glossy, you can start with 600 and go up to 2000 grit (you can get those high grits at autofinishing places).

    If you're using the tru-oil to get some kind of depth on your finish then you can probably sand to 600-800 grit before spraying and that should be enough.

    I hope you've read about compatability betwen tru-oil and polyurethane, because I haven't.
     
  6. For fine-grit sandpaper (not steel wool), you might try some auto-supply stores.

    edit: Wilser got here first.
     
  7. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
  8. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    It looks like I might not have access to the air compressor and spray gun, after all...
    Then it's going to be wipe-on poly...
    Anything I should watch for with them? I haven't painted anything so far... :ninja:
     
  9. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    I'm in the process myself right now.
    1) sand with 320 to 400
    2) Tru oil as many coats as you want. It does build a nice finish by itself, but it is not a very hard finish. Let the tru oil dry a minimum of 2 hours between coats. I would recommend 4-6 hours.I applied 10 coats.
    3) I then applied Minwax wipe on poly and wondered why I wasted so much time with the tru oil. The Minwax is a thinner finish and goes on much smoother, but dries much harder. The finish just looks like glass. I would apply at least 2-3 coats of the Minwax. Oh, it's time for another coat. Bye.
     
  10. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    Thanks!
    Minwax is most probably not available here, but I'll try to find something similar.
     
  11. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    If you can't find the Minwax you can thin any good poly with mineral spirits. Maybe 50/50? Experiment.
     
  12. In my experience there is 100% compatibility between a TO finish and polyurethanes - even the more agressive types of 2 and 3 part catalyst hardened versions used in automotive systems. Case in point is my Fairlane project. The body was completely finished in TruOil before have the 6-8 coats of PPG Dimension 2000 Poly applied on top. Take a look at the pics in the thread.
     

  13. The reason you went the TO route is that the oil soaked into the wood before it hardened - something the wipe on poly doesn't do as well. By soaking in, the oil will magnify and enhance any figure the wood presents and you'll get it to show up better. The poly on top is a better protector than the TO and will build quicker. You did the right thing.
     
  14. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    I know that the Tru Oil was the right thing to begin with. There is nothing like the beauty of an oil finish. I just wish I had not applied ten coats of Tru Oil. I think fewer Tru Oil and more coats of Poly would have given a harder finish and been easier to do. That said, the bass is gorgeous.
    Need to get a good digital camera.
     
  15. shameandspite

    shameandspite

    Oct 12, 2005
    I hate to refer you to a town killing, mass business, corporate, "evil institution" (in my opinion, no flaming please). But just wandering if they have wal-mart in budapest? Probably not. They have steel wool there as well as substitutes.

    I'm ashamed I know that. I'll be praying to the small town deities.
     
  16. Frank Martin

    Frank Martin Bitten by the luthiery bug...

    Oct 8, 2001
    Budapest, Hungary, EU
    No Wal-mart here. Yet.
    However, there are the European equivalents...
    Still haven't gotten round to look for steel wool, but hopefully I'll find some somewhere. I was a bit busy with tomorrow's french exam(s), the electronics (can't find 500k push/pull log pots now :rolleyes: ) and my birthday ^^"
    I'll try one of these bigger hobby/diy places.

    One more question.
    I'm having trouble identifying satin... :oops: :D I'm guessing it's not a glossy, glass-like finish, not even matte, but somewhere in-between, a bit more natural, sort of like what a buffed oil-and-wax finish looks like?

    Oh and one more. What type of screw is in the strap button (more specifically a Dunlop straplock, but it's not here yet, so I have no idea about it's size... but I have to drill the hole before the finish)

    Thanks!
     
  17. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    I use Watco Danish oil. I guess it's like TruOil. I do that only to give the wood a nice color... let it dry two days, and then spray catalyzed lacquer over that.
     
  18. This is my MO recently but I'm using 3 part poly for my coating. Watco makes another oil I'd like to try - "Tried and True" oil. It's a true polymerized linseed oil concocted by an old recipe and it's supposed to be the finest around.

    Nothing beats the light "stain" that oil gives wood.
     
  19. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    Hambone,
    Fine Woodworking did a survey of DIY finishes in their August issue. Hate to burst your bubble, but the Tried and True scored near the bottom. The problem as I recall was that it was very thick, yet never really dried.
    YMMV of course.
     
  20. Greg Clinkingbeard

    Greg Clinkingbeard

    Apr 4, 2005
    Kansas City area
    Setup and repair/KRUTZ Strings
    Yes, a Satin finish is just a lower gloss finish. I still think the Minwax Satin is pretty glossy, however. If you want Satin and can't find it you can rub the bass down with 0000 steel wool and buff it with your bare hands. This gives a nice, Matte finish.

    I can't help you with the strap button holes, but I drilled mine after the finishing process and didn't have any problem.