Correction of poor finish

Discussion in 'Decorating and Painting' started by mellie_man, 30 Jun 2018.

  1. mellie_man

    mellie_man

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    hi

    I just painted exterior woodwork and decided to make the change to water based weather shield, as I was doing front door. Wrong week to do that. Temp is so high that paint was drying as I applied so finish is flat and brush marks visible.

    So my question is can I rubdown and put a second coat of gloss or does this not work with The new formula WB paints. Do I need to re undercoat as it dries so quickly.
     
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  3. JohnD

    JohnD

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    the water based gloss paints can be hard to sand as they form balls of paint.

    try it with minimal pressure and quite a fine paper.

    I presume that eventually they harden enough for it to get easier, but I don't know how long it takes.
     
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  4. opps

    opps

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    Sanding it should be sufficient, however, most waterbased paints are a mare to sand. They tend to gum up the sand paper. You may be able to scrape the finish off using a plastic scraper (try to scratch it with your fingernail first to see how soft it is).

    When you recoat, add some Floetrol to the WB weathershield. It isn't cheap but well worth the money. It extends the wet edge and helps the paint flow without slowing the rate at which the paint cures.

    https://www.owatroldirect.co.uk/product/floetrol/
     
  5. ic1927

    ic1927

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    Leave it for a week to fully cure, then it should sand down fine, and use silicone carbide (wet and dry paper).
     
  6. opps

    opps

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    I have just finished painting a hallway. The last two times that it was painted the decorators use Farrow and Ball eggshell (which has been water based since about 2008) on the woodwork.

    The woodwork took between 5 and perhaps as much as 10 times longer to sand flat because of the waterbased finish. The last coat of paint was applied about 5 years ago, and thus was fully cured. It didn't gum up the paper on my Festool sanders but I suspect that it creates microballs of dust which reduce the cutting ability of the sand paper. It is almost as if the paper is bouncing over the surface rather than sanding it.

    I have thousands of pounds worth of sanders and dust extractors and am happy to spend whole days just sanding, however, I groan when faced with waterbased finishes.
     
  7. ic1927

    ic1927

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    I know what you mean, some of the water based finishes can be a nightmare, especially made worse when the last decorators haven't prepared the woodwork properly. Had a job a few years back where as soon as I started sanding the lot came off in sheets, what a mess. They had just dolloped it on straight over old oil gloss with zero prep and had used some b&q own brand water based satin ****e. I find wet sanding helps if the water based stuff is stable enough.
     
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