polyurethane (minwax) polishing

Discussion in 'Luthier's Corner' started by joeyl, Dec 28, 2009.


  1. joeyl

    joeyl Supporting Member

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    Jun 3, 2006
    Location:
    New Orleans, LA /El Paso TX
    I have always used nitro lacquer for bodies since the layers melt in and are easy and simple to apply and repair. However it is a fragile finish. I have used the wipe on and spray on poly on necks with good results. Can the 1-part polyurethane be buffed to a high gloss like nitro? Anybody wants to share pics or tips? For nitro polishing I use abralon pads, can I use the same for Minwax poly?

    thanks
  2. Lonnybass

    Lonnybass

    Joined:
    Jul 19, 2000
    Location:
    Minneapolis by way of Chicago
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    Endorsing Artist: Pedulla Basses
    Having used Minwax poly several times and, more recently, experimenting with varnish and oil/varnish blends, I would guide you away from using Minwax poly as it can be difficult to buff out to an even high-gloss finish. Yes, it's possible, but a lot of work and very much a two steps forward, one-step back proposition. Not to mention that it isn't easily repaired and lends a somewhat plastic look to wood.

    Are you open to going a different route? Check out some of my recent build threads to see what kind of luck I've had with the varnish rather than poly.

    Most recently, the example bass you see below which began to cure yesterday. This was finished with a wipe-on oil/varnish blend under several topcoats of thinned varnish. Loads of grain popping, lots of color, some ambering and darkening without looking unnatural. Application-wise, I found that it is much easier to work with than polyurethane as well, of which the thinned wiping versions tend to run no matter how diligent you are. I may never use polyurethane again.

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  3. joeyl

    joeyl Supporting Member

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    Location:
    New Orleans, LA /El Paso TX
    looks nice and glossy! I'm open to different methods :D However my first few Warmoth assemblies were finished with oil blends and varnish. I like it but the process is slow. And I have 2 long haired dogs that run around a lot, so everything that has a hand rubbed finish takes a lot time to flash dry, and I get a lot of hair that need to be sanded off. Lacquer and the Minwax polyu dry to the touch rather quickly before foreign stuff gets to stick to it.
  4. Lonnybass

    Lonnybass

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    Jul 19, 2000
    Location:
    Minneapolis by way of Chicago
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    Endorsing Artist: Pedulla Basses
    Yep the process certainly takes some time and I understand the challenge of working around pets (I've got two myself). I would say though that a varnish thinned with naptha will be essentially tack free within about four or five hours...and more importantly - is WAY more forgiving in terms of removing inevitable dust nibs, runs and other particulate than polyurethane if you put on thin coats. With light scuff sanding in between coats at about 320, you should be able to get off all the little nasty bits and stuff as you build successive coats.

    Lonnybass
  5. 62bass

    62bass

    Joined:
    Apr 3, 2005
    You could try one of the new fast drying alkyd varnishes such as Benjamin Moore One Hour Clear Finish. There are two other brands that are similar made by Sherman Williams and Zinsser. They dry to the touch in minutes so dust contamination is minimal. They can be recoated in one our two hours depending on temperature and dry hard.

    I use the Moore One Hour Clear Finish in gloss and wipe it on thinned 50/50 with naptha. Get 3 to 4 coats a day on easily.

    After a week or two it can be rubbed out to a mirror gloss if desired.

    You have to practice with it first. The drying time is so fast that it's tough to keep a wet edge and you can't go back to "tip off" the finish or fix missed spots. I've been using it a lot for about 6 years or more. It looks and feels much nicer than poly. I will never bother with polyurethane again.

    Lonny has some experience with it too.
  6. scottyd

    scottyd

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    Nov 17, 2006
    Location:
    Waco Tx
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    Builder/owner Redeemer Basses
    I've had great results with Minwax poly. The only downside I've found it cure time is pretty long. If you try to buff/rub before it's fully cured you'll have problems. But other then that it buffs the same.

    Keep in mind I'm not talking about spray cans, spray cans suck. Do yourself a favor and buy a nice HVLP spray gun. Buy the poly in either quarts or gallons and practice using it. You can thin it with mineral spirits There’s loads of info on the net about thinning and spraying poly. Once you get your thinning and application right and you'll be able to apply a near perfect finish with little to no orange peel. THE POLY ITSELF IS GOOD but it requires good technique to apply it.

    Spraying with cans always causes extra work what I’m referring to is un-even build up, orange peel, thin coats ect. I guess it’d take a good 5-6 coats with a spray can to match the mil thickness of 1-2 coats with a quality gun.
  7. Lonnybass

    Lonnybass

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    Jul 19, 2000
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    Minneapolis by way of Chicago
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    Endorsing Artist: Pedulla Basses
    +1! :cool:
  8. Headless Llama

    Headless Llama

    Joined:
    Aug 15, 2009
    Location:
    West Bend, Wisconsin
    I used the Minwax Poly on my walnut bass. I really liked using it. The only down fall is that you have to be patient with it. I got a really nice shine on mine, it looks "real" not like plastic.
  9. joeyl

    joeyl Supporting Member

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    Jun 3, 2006
    Location:
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    Thanks Lonny and 62bass, I'll check the varnish out. To scottyd, I can't justify an hvlp setup yet, but it is quite tempting because I have several pieces of wood furniture awaiting refinishing, like bookshelves, maybe I can persuade my wife that I need a compressor and gun setup :ninja: If I buy a gun then I would try the water based polys! To headless: yeah I have used Minwax poly on maple necks and they feel as good as any other if applied thinly.
  10. pilotjones

    pilotjones Supporting Member

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    Nov 8, 2001
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    US-NY-NYC
    Do these alkyd varnishes burn one layer into the previous, or do they stay separate so you still need to worry about witness lines when sanding?
  11. joeyl

    joeyl Supporting Member

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    good question, I want to know too
  12. Lonnybass

    Lonnybass

    Joined:
    Jul 19, 2000
    Location:
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    Endorsing Artist: Pedulla Basses
    I believe witness lines are indeed possible. If you have the patience (and sandpaper grits) for it, you can blend the lines out.

    Lonnybass
  13. 62bass

    62bass

    Joined:
    Apr 3, 2005
    No they don't and that can be a problem with witness lines. However, the Benjamin Moore One Hour Clear Finish I've been using has not given me a problem so far. I looked at the ingredients on the label and they include some pretty potent solvents including xylene. Perhaps it does slightly soften the previous coat if recoated soon enough. I don't know for sure. I scuff sand and recoat within 2 hours usually. I'm pretty careful too when sanding the final coat to not cut through. The final coat, if the previous ones have been carefully levelled and are flawless, dries almost perfect and needs no levelling really. When I have some time I plan to do some more experimenting and see if I can go directly from a cured final coat to automotive polishing compound and abralon pad. I suspect I will.

    Anyhow, I like the look and the fact that I can apply so many coats in a short time. The results have been great now that I have experience with it. There's an articl;e explaining this method in an old issue of Fine Wooworking written by Jeff Jewitt. While I have been doing it with conventional alkyd varnish for years before that article he was the one who used the fast dry varnishes. The Benjamin Moore and I expect the Sherman Williams and Zinnser versions, have vinyl toluene added to give the incredibly fast dry time. That, combined with the thinning with naptha makes it dry almost as fast as lacquer.

    On a somewhat related note-this morning I was doing a bit of painting of some wood trim at home using a good brand of semi gloss acrylic latex. It's so dry inside that it was impossible to keep a wet edge and the paint dried before levelling leaving terrible brush marks. I checked the humidity reading in the room and it was 25%! Man, that's dry. It's near that outside too and combined with the furnace going so much with this cold snap, it's dry as a bone. I have used a product called Floetrol before which slows the drying time of water based paints. I should have used it this time..
    But a lot of people are very happy with polyurethane too. Myself, I won't go back to it but if they get good results, that's perfectly allright.
  14. joeyl

    joeyl Supporting Member

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    Jun 3, 2006
    Location:
    New Orleans, LA /El Paso TX
    That would be a problem for me since I am currently in west Texas (El Paso) humidity on a normal day is around 25% :)

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