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Oil Based vs Water Based Polyurethane

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  • Oil Based vs Water Based Polyurethane

    Will I get less of the tiny little bumps using an oil based poly in lieu of the easy clean water based product. Secondly can someone recommend a buffing compound to use after a super fine grit sanding without affecting the gloss of the finish.

  • #2
    Automotive buffing compound will buff it out, but may affect the gloss. Auto polishing compound will give you a high gloss finish and rubbing compound will be a bit less gloss. Use it on a trial piece first to get the effect you want.

    As far as the tiny bumps, that can be caused by dust or grit getting in the finish, gas bubbles from the poly reacting with moisture, or air bubbles from the coating being too thick. If its not moisture or contaminants like dust, etc, the culprit is usually the quality and age of the poly.


    Practicing at practical wood working


    • #3
      I get a lot less bubbles when I first use a coat or two of sanding sealer.......those bubbles are very frustrating.


      • #4
        A quality foam brush like those sold at LeeValley go a long way in preventing those bubbles.
        "Did you put the yellow key in the switch?" TOD 01/09/06


        • #5
          I don't know the reason but I started seeing less bubbles in my poly when I stopped using MinWax oil based poly and switched to ZAR oil based poly. The ZAR poly also has a much faster dry time.
          I decided to change calling the bathroom the "John" and renamed it the "Jim". I feel so much better saying I went to the Jim this morning.


          • #6
            you can try thinning your finish as well to make it a "wiping" finish. most commercial wiping finishes are just diluted down 50:50 with mineral spirits and then they charge you more. I make mine with a 1:3 mixture of mineral spiritsolyurethane. when you wipe in on, if you do it with a little paitence you won't get bubbles, it dries a little faster so less dust nibs, and it's great for vertical surfaces- less drips and runs. the downside is that you get less finish applied, so it takes more applications.

            I also like a good foam brush when I don't wipe- less bubbles and brush marks.

            as far as rubbing the finish, I've had good success with super fine steel wool (0000). doesn't take off much finish, creates a very smooth surface, and unless you go crazy doesn't take off too much gloss. i do this after the first and last coats, sanding between others.

            just remember, the more gloss you have, the more little imperfections like brush marks, bubbles, dust, etc will show up. but it's all a matter of preference. satin all the way for me.


            • #7
              Originally posted by kayakpeak
              Will I get less of the tiny little bumps using an oil based poly in lieu of the easy clean water based product. Secondly can someone recommend a buffing compound to use after a super fine grit sanding without affecting the gloss of the finish.
              One quick question.. how are you mixing the poly before applying. Just double checking you arent shaking the can.

              I am about to start finishing my cabinets in the house and i was warned not to shake to mix because it will put all kindsa bubles in.



              • #8
                The primary reasons for getting "bubbles" in your poly is the turbulence created by either shaking, briskly stirring, or, in most case, brushing. Wiping or using a foam type applicator will reduce the occurance of bubbles, but may not eliminate them entirely.

                From my experience, the creation of the bubbles is only problematic because most polyurethanes are simply too thick, and it begins to set before the bubbles have a chance to rise to the surface and escape.

                I just completed the refinishing of the red oak wainscote that is in the kitchen of the older house that will soon become our new residence. I think this kitchen had been remodeled within the last decade, but thanks to the previous owner's poor housekeeping and their pet cats, the wainscote was a mess. With new cabinets and a re-design of the layout, half of the these red oak planks had to be removed anyway. Tough job because in addition to the trim head screws they used, it was also glued to the wall. None of the trim molding came off without some damage.

                Fortunately there was only one thin coat of finish on the planks and it was easy to remove. The thick adhesive on the back of these planks had to be taken off with a chisel and mallet, and then belt sanded to give me a consistant mounting surface. I sanded the plank faces down to a new surface (including the beveled edges), and then cleaned it thoroughly with mineral spirits.

                My first coat of poly was thinned to just about 50/50, using oil-based gloss finish. After a couple of days of curing, a light sanding with a synthetic pad followed, and then a wipe down with an old t-shirt dampened with mineral spirits. I used the "gloss", because I figured it was easier to inspect when dry, thus ensuring against any missed areas.

                The second coat was semi-gloss with the poly thinned to about 80/20. A careful eye is needed to ensure against drips and missed areas. Again, a light sanding with the synthetic pad. The last coat was the same mixture; 80/20, semi-gloss/mineral spirits. The end result came out quite nice, IMO. I wanted it protected and easy to clean, but I didn't want the surface to look plastized to the point where the wood texture was lost.

                Initially I had considered spraying on the final coat(s), but since half of the project was still on the walls, I couldn't see a way to prevent fallout from the spray, effecting the rest of the kichen. Actually the wainscote in the kitchen was less challenging than I thought, since temperature and humidity was better inside. A couple of planks that I finished in the garage, show a couple of small specks. These had been done at mid-afternoon when the temperature was beginning to get uncomfortable, and the poly was setting rather quickly. You'd have to get really close to spot these "defects" though.

                I used oil-based poly. First because I wanted the warmer coloring and second, because I've read that the water-based, polymers don't bind as well, and over time may be less protective. Water-based polyurethance (at least the Minwax products) usually dry clear. I figured that's great if you like the color of whatever you start with, but I wanted the warmer amber that the oil-based product brings.

                I hope this helps,

                Last edited by CWSmith; 06-14-2006, 02:30 PM.