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wipe on poly and tack cloth

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  • wipe on poly and tack cloth

    Question, when sanding polyurethane in between coats, using a tack cloth, is it ok to wipe on poly while the project seems tacky or should a person wait a few hours to let it dry?
    How necessary is it to sand between coats of polyurethane? I am sure people have a lot of different opinions and different ways of finishing. There may be other finishes but Minwax polyurethane (oil base) is good enough for me. How many coats of wipe is necessary and how long between coats? thanks dan

  • #2
    I use wipe on poly quite often and I apply 2 thin coats before sanding with 220 or 320. I wipe with a lint free. Someone told me not to use tack cloth as you can leave behind a wee bit of beeswax witch could cause issues later on.

    I make sure that the surface is dry and not tacky before adding more coats. I can't say for sure but a couple of hours indoors. I can get 6 coats on in one day if I need so. I put on very thin but if in a hurry I will on a little thicker and get away with 3 - 4 coats.
    After the sanding after the third coat I will either sand with 320 or start using the phony steel wool. Green or white.

    I also prefer the oil based satin finish but Min wax does not list on there site anymore so I hope it is not going away.

    I have used the Zar water based and it was okay but it seemed like it raised the grain and took more sanding.

    Don McFarland ​Member - Durham Woodworking Club http://www.durhamwoodworkingclub.com/

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    • #3
      First, follow the instructions on the can, regarding wait time between coats. I would think that for the first couple coats, re-applying while the previous coat was still tacky wouldn't be terrible, but I would warn that building several coats without allowing proper drying time, will extend the overall, full cure time and may impede complete curing, so there really isn't much to gain.

      As for sanding between coats, it's typically recommended to sand if a specific amount of time has passed since the previous coat was applied. The need for sanding with polyurethane is because it does not bond all that well to itself (or other finishes, for that matter) after it has dried past a certain point. A light sanding provides some tooth for the next coat to adhere to, if the previous coat is dry beyond the stated # of hours. If you are applying in less than the stated # of hours, then you don't need to sand for adhesion, because the previous coat is still soft enough to allow the next coat to bond. So, there is a window, within the application/cure lead time, in which re-application is best done. The manufacturer's instructions should specify this.

      Now, if you are sanding to smooth the surface, that's a little different. With a wipe-on poly, I don't think sanding for smoothness, between each coat is necessary. Sand smooth between the last couple of coats, but it's best to wait until the finish has thoroughly dried.
      Sanding too soon will only clog up your sandpaper.

      Again, the instructions on the can should provide the info on required and recommended drying times for all the operations.
      Homer : "Oh, and how is education supposed to make me feel smarter. Besides, every time I learn something new, it pushes some old stuff out of my brain."

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      • #4
        Like Bill said the sanding is for adhesion not smoothing.
        I use several wipe on finishes. Gel varnish for my intarsia and the wipe on polyurethane for larger surfaces. like a dinning room table. The advantage is you don't have a thick slow drying layer to gather specks of dust. Two or three coats as recommended with the light sanding between coats.
        Rolf
        RBI G4 Hawk, Delta SS350, Nova 1624 DVR XP
        Philosophy "I don't know that I can't, therefore I can"
        Proud Member of the Long Island Woodworkers Club
        And the Long Island Scrollsaw Association

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        • #5
          I decided to finish with spray polyurethane, I did brush on a few coats, I loose track of how, may coats especially when the top is one day and the bottom is the next day. I have used wipe on in the past, it is ok.
          Does any one do anything after the final coat, of spray on polyurethane? I was thinking spray wax like lemon pledge? There are 2 dowels that fit in the base to hold the outside of the cross which may need waxed?
          Hopefully this is the last coat of poly. I am anxious to have this done and anxious to post pictures.
          Oh and I am fanatical about leaving things cure before they are handled.
          Thanks so much for any replies.

          And I hope to soon have the other project done I started over a year ago. The one with the lacewood crack.

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          • #6
            We all have our preferred methods. Air temp, humidity or lack of, what types of wood were used, etc.----they all make a difference in what works "best". What matters most is what gives you the best results you are trying to achieve. Experimentation gives us some things to learn from (the do-not repeats)....and sometimes some awesomely remarkable results. Good luck!
            Linda at www.ArtIngrained.com

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