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Thread: Wipe-on poly cloudy after light sanding

  1. #1

    Wipe-on poly cloudy after light sanding

    I used some Minwax wipe-on satin-finish poly on the top of a mahogany bureau using a paper towel to apply. I have used this can and application method many times in the recent past successfully, but often without sanding between layers. After reading about the necessity of sanding to give the surface some tooth for the new layer to adhere to, I followed the Minwax instructions. I had a problem.

    1. I wiped on a layer of Minwax wipe-on poly after dying (TransTint with water as solvent), sanding (to knock down the grain), and staining (Zar oil-based, almost a gel) the mahogany top.
    2. After 3 hours (about 70-75 degrees) I dry sanded very lightly (1-2 light drags back and forth) with 220 wet/dry paper.
    3. I wiped on a second coat.
    4. After 20 hours I dry sanded very lightly (2-3 light drags back and forth) using same paper and block as above.
    5. The finish became cloudy. The second subsequent layer I wiped on (no sanding in-between) pretty much eliminated/covered the cloudiness.

    What did I do wrong? THANKS

    PS The sand paper shown is the sand paper used. The build-up of finish is from this piece - I figured it would decrease the abrasiveness if it had any effect at all. This paper has been used only on this piece (I am just doing the top).
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    Doug, the "Wood Loon"
    Acton, MA

    72, slow road cyclist, woodworking dabbler, tool junkie , and
    bonsai enthusiast.
    Now, if I could just stay focused longer than a few weeks...

  2. #2
    I think you're doing it right. Every time I sand between coats, it looks milky like you're seeing. The next coat eliminates it.

  3. #3
    Join Date
    Mar 2003
    Location
    Southport, NC
    Posts
    3,147
    As I said on the other forum, if you sand a finished surface with 600 paper you creating a lot of fine scratches. Sanding is scratching. Sanding with 600 grit paper will give you a satin finish. If you want a gloss finish, do not sand after applying the finsih. Poly varnish will never be more glossy than it is right out of the can.
    Howie.........

  4. #4
    Quote Originally Posted by Howard Acheson View Post
    As I said on the other forum, if you sand a finished surface with 600 paper you creating a lot of fine scratches. Sanding is scratching. Sanding with 600 grit paper will give you a satin finish. If you want a gloss finish, do not sand after applying the finsih. Poly varnish will never be more glossy than it is right out of the can.
    First, thank you for all your erudite postings. They consistently impress me.

    The poly I am using is a satin finish without any sanding - I am pleased with the reflectiveness (correct word?) without any scuffing. I used 220 grit because that was what Minwax suggested. I was not worried about the scratches, I was concerned about the cloudiness.

    On a separate issue, is 600 paper (or 0000 steel wool) an appropriate way to cut down the gloss on shellac? Does Homestead Finishing's shellac flattener work?

    Thanks, as always.
    Doug, the "Wood Loon"
    Acton, MA

    72, slow road cyclist, woodworking dabbler, tool junkie , and
    bonsai enthusiast.
    Now, if I could just stay focused longer than a few weeks...

  5. #5
    Join Date
    Dec 2006
    Location
    Toronto Ontario
    Posts
    11,248
    Doug, on the last coat I sand with #600 lightly, then apply a couple of coats of paste wax.

    You might try that out........Regards, Rod.

  6. #6
    Join Date
    Mar 2003
    Location
    Southport, NC
    Posts
    3,147
    The photo you posted shows clearly that the surface has be unevenly sanded. I would suggest you scuff sand with 320 paper on a sanding block sanding in the direction of the grain. Vacuum off the dust.

    Mix your finish completely. The flatteners added to the finish to give you a "satin" gloss quickly fall out of suspension in thinned wiping varnish. Re-mix frequently while coating. The cloudiness is the uneven distribution of the flatteners in the finish.

    Put on one more coat smoothly and you should end up with a satin finish. Do not sand the final coat.
    Howie.........

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