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Water-Based Polyurethane

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  • Water-Based Polyurethane

    I'm hoping some of you furniture builders or finishers can help me. I have been building, restoring, and refinishing heirloom furniture for more than 40 years but I have recently run into a problem I cannot solve. My daughter wanted a table for her hall (6' x 15" x 2.5") veneered in quilted maple. She also wanted to retain the almost white color of the maple. My preferred finish is Zar oil-based polyurethane rubbed between coats and finished off with a 3,000 grit Abralon pad. However, because oil-based poly gives a honey or amber tint to the wood my only choice was to use a water-based poly in order to retain the very light color of the maple. I'll state here that I have never used a water-based poly.

    I bought Varathane water-based poly at HD and brushed it on, which is my preferred way of applying finishes. Even though I was using a high-quality Purdy synthetic brush, it left brush streaks and "roping." Even after adding XIM drying extender, I still get the roping. I tried Minwax brand or water-based poly and got the same result. I tried spraying the finish on and it was a disaster - leaving an "orange peel" texture.

    I have sanded off the finish four times and am just about ready to buy her something from a local furniture store!

    Anyone have any comments, suggestions, recommendations on applying the water-based poly? Is there another product out there easier to use?

  • #2
    I see no replies yet, but hopefully some of the more experienced members will step in soon.

    Let me state that I have never used water-based poly, so can't offer any specific experience here. I've thought about it a few times, but that's the extent of it.

    However, I do read a lot and after seeing that you have yet to receive a reply I thought I'd offer at least something. So, I picked up my Taunton Publishing's Illustrated Guide, "Finishing" by Jeff Jewitt (maybe your library has it). On page 261 there is a section titled "Flow-Out and Foaming" where he states ideally such finishes need to be applied at around 70? F. Further he states"

    "that your project and environment are at least at 65? F. Failing that, you can try to add a retarder available from the manufacturer to slow down the drying.
    However, I recommend always trying to correct problems without adding anything to a water-based finish.
    A water-based finish may look terrible right after it is applied. It may not flow out and level quickly, like solvent-based lacquer or shaellac. But be patient; coalescing takes time. Let the solvents in the finish do their job. It's not unusual to leave a hopeless-looking finish at night only to find a perfectly level, clear finish the next morning."

    On a side note, the author mentions that the only additive you can safely add without causing problems is distilled water, usually up to 20 percent for a clear finish. Basically the problem lies in the chemistry of water-based polyurethane. The best advice should come from the manufacturer of the finish product, as they know their chemistry and what kind of steps may be required.

    Really sorry that may not be more helpful, but like I said, I have no experience there. I will look forward to whatever someone posts.



    • #3
      Thank you for your advice. I will review the article you referenced on my next trip to the Chattanooga Library.

      I did look at several articles on water-based poly in other books I have. The best was in a Woodsmith publication, Top-Notch Finishing, I picked up at their Des Moines store a couple years back. Unfortunately, I have found that many articles apply only to small, hobby-type pieces and not the larger furniture items. It makes me wonder sometimes if the advice columnists have ever tried their own advice.

      Earlier this morning I called the technical services department at Rustoleum, who makes the Varathane water-based poly I am using. Their only viable recommendation was to add a bit of distilled water (following your advice) or XIM Drying Retardant to slow down the drying process. I was already using about two ounces of XIM per quart and it was still drying too quickly. Their chemist said I could safely add up to four ounces of XIM per quart. I'll give that a try this afternoon and apply the finish as quickly as I can.

      Thank you again for your advice. My daughter should appreciate this project because water-based poly will never find its way into another project of mine!


      • #4
        Well good luck with your project. I hope the XIM works out for you. I'm sure your daughter will appreciate your efforts.

        Have you thought of using lacquer? Back when I used to do a lot of illustrations on the drawing board, we used to use Krylon spray lacquer to finish the piece, as you don't want it to be spoiled by handling. I've used canned lacquer to spray a couple of small finished wood projects. Problem with spraying, which I prefer, is that it's challenging because it dry's so quickly. I've never tried brushing it.



        • #5
          Yes, I have used lacquer on restorations of brass and very small wooden accessories, but it doesn't build sufficiently to produce a flat "piano" finish for larger pieces. My absolute favorite finish is Zar oil-based polyurethane. It builds quickly, slow drying so very few brush marks and is like an armor coating on furniture.

          FYI - I wound up adding three ounces of XIM to the water-based poly before the drying time slowed enough to prevent overlap marks. Even then, I had to load the brush heavier than normal had hustle with the application. It is turning out to be a beautiful piece. Tomorrow I'll do the final graduated rub with #600, 800, 1000 and 3000. Then polish it off with a light coat of Mylan's wax before delivering it Saturday morning. This project definitely calls for a couple glasses of gin!


          • CWSmith
            CWSmith commented
            Editing a comment
            AMEN on the gin!

            Very happy to hear the finish is working out for you. Post a couple of pictures if you can.

            Thanks for the update,


          • Bob D.
            Bob D. commented
            Editing a comment
            I'm surprised that the finish is dry enough since you just started two days ago. I know WB poly dries faster than oil-based but I would want to wait a few more days before I delivered it as 'finished'.

        • #6
          Here are a couple of photos