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Polyurethane Problems with Pine

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  • Polyurethane Problems with Pine

    I've stained a platform bed made of white pine with an oil based stain. The stain can said it would dry in 5 hours; so 5 hours later I tried to apply a water based polyurethane, but it pulled the stain off where the wood had knots. So I let the poly dry, then sanded it down to reapply the stain that was removed on the knots. Then I waited another 20 hours to make sure the stain would dry and tried again. It did the same thing; removed the stain over the knots!

    What's going on?

  • #2
    Re: Polyurethane Problems with Pine

    I've had the same problem with pine, mostly using MinWax stains. All too often, it just doesn't penetrate and therefore sits on the surface. I've never tried using water-based poly, but I do know that the oil-based poly will simply wipe off the stain if it didn't penetrate; and this, I think, would be especially true on knots. Not only because of their density, but also for the concentration of pitch that is evident.

    I've used the Minwax Polyshades with more success, as it is a mix of poly and stain. But even with that, I've found it advantageous to wipe down the pine with mineral spirits, in an effort to diminish the pitch that seems so prevalent in most of the pine today. Varathane and some of the other brands may be more successful, although I think you'd run into the same challenges.

    Perhaps it's just me (memory of wood long ago, seems like it was of much better quality), but today's pine seems like it's harvested much too early, not properly dried, etc. It used to be that you could buy stock that was clear and only when you bought the worst grade did you run into bark, pitch, splits, twist, and more knots than you can count. Today, that seems to apply to even the "premium" marked grade.

    I hope this helps,

    CWS
    Last edited by CWSmith; 08-02-2007, 12:30 PM.

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    • #3
      Re: Polyurethane Problems with Pine

      Using sanding sealer after the stain would probably help a lot.

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      • #4
        Re: Polyurethane Problems with Pine

        So I guess my only option now would be to apply the sanding sealer since I've already applied a stain and can't try the polyshades. I was wandering if using an oil stain and water poly had anything to do with it, but it sounds more like bad quality wood. The sanding sealer won't strip the stain off like the poly did?

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        • #5
          Re: Polyurethane Problems with Pine

          I have had really good luck with ZAR stains, drys slow but seems to give an even stain and does not wipe off when applying poly. Does seem to stain darker than the samples at the store
          Please check out my web page
          www.woodandwax.net

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          • #6
            Re: Polyurethane Problems with Pine

            Originally posted by wellington View Post
            So I guess my only option now would be to apply the sanding sealer since I've already applied a stain and can't try the polyshades. I was wandering if using an oil stain and water poly had anything to do with it, but it sounds more like bad quality wood. The sanding sealer won't strip the stain off like the poly did?
            Among other things sanding sealer is supposed to specifically be used to seal the stain in place so it doesn't get wiped away or bleed through the poly. I would give it a test in a scrap piece to see how it performs before trying it on your project. I find it interesting that water based poly will pull away oil based stain given they use different solvents. I've actually read that this is a good idea precisely becuase of that. I would figure that would be the case with oil based poly since its solvent would dissolve the oil based stain as well.

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            • #7
              Re: Polyurethane Problems with Pine

              well i put the sanding sealer on and it did the same thing; took the stain off of the knots. but, it seemed to be not as bad, so i am just going to finish the project. i guess pine from the big lumber stores is worthless. lesson learned.

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              • #8
                Re: Polyurethane Problems with Pine

                "well i put the sanding sealer on and it did the same thing; took the stain off of the knots. but, it seemed to be not as bad, so i am just going to finish the project. i guess pine from the big lumber stores is worthless. lesson learned.

                It's not the fault of the store, it's the nature of the wood. Pine knots are near solid sap filled. I've done lots of knotty pine jobs and my only success is by really scrubbing the knots with lacquer thinner just before staining. This will remove the resins from the surface of the knot and give me a chance at success. I then spray on a 25% mix of sanding sealer lacquer and 75% thinner to even up the porosity of the wood. (called a "wash coat") It dries in minutes and I then stain it. For me, its a spray on of either Minwax or a custom mix from Frazee. I wipe off the excess and let it dry a few hours then give it 2 more coats of regular lacquer sanding sealer. Let it dry good, sand with 220 and then 3 coats of semi-gloss lacquer, all sprayed.




                Using a brush on finish over anything stained is a crap shoot for me. The brushing usually just ends up moving some of the stain around and leaving a real mess. I've tried the Polyshades too and personally, I think they suck! But that's just me.

                Mark
                Congratulations to Mr. "the sky is falling" Al Gore, nominated the new Village Idiot!

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                • #9
                  Re: Polyurethane Problems with Pine

                  Originally posted by The Wood Meister View Post
                  [I]

                  Using a brush on finish over anything stained is a crap shoot for me. The brushing usually just ends up moving some of the stain around and leaving a real mess. I've tried the Polyshades too and personally, I think they suck! But that's just me.

                  Mark
                  It didn't dawn on me until Mark pointed out the spray vs. brush - I just assumed you were spraying the water-based poly. Water based poly dries very quickly compared to typical oil based poly to the point where it seems to get sticky (tacky) almost immediately. Any over brushing is much more likely pull away any stain that isn't stuck down well. The only way I apply water-based poly is to spray, and if I've used an oil stain, I wait at least 24 hours before spraying the finish.

                  Jim

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                  • #10
                    Re: Polyurethane Problems with Pine

                    Yep, the consensus is to spray the topcoat so that you don't disturb the shallow staining on the resinous parts. Mark, that's some beautiful work, man. I think that pine is highly underrated. Years ago ('79) I did a kitchen in pine, stained gray. I still wish I had that kitchen.
                    Later,
                    Chiz

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