Q&A for How to Apply Polyurethane

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  • Question
    Is it colorless and if so, can color be added to it?
    Community Answer
    Water-based poly is colorless. Oil-based poly turns amber over time. You can stain or paint the wood before applying the poly.
  • Question
    What materials are used for filling the cracks and gaps in wood ?
    Community Answer
    Use wood filler. Use a spatula for application. Allow the filler to completely dry, then sand it down for an even surface.
  • Question
    If I've applied a color stain to the wood, should I really be sanding between coats? I don't want to inadvertently remove the stain.
    Community Answer
    Sand very lightly using a fine grit sand paper. You only want to "rough up" the surface of the previous coat to give the next coat better adhesion.
  • Question
    Can I use a paint pad for the second coat?
    Community Answer
    Yes, a paint pad should work fine.
  • Question
    Does polyurethane turn yellow or brown as it gets older?
    Community Answer
    Water-based poly remains clear, but oil-based poly does turn an amber shade over time.
  • Question
    Can you apply polyurethane over a painted wood trim to get a glossy finish?
    Community Answer
    Yes, as along as the paint is dry.
  • Question
    Can I just apply one coat?
    Community Answer
    Using two coats is typically advisable because this provides better protection and a more even finish.
  • Question
    Can I apply polyurethane outside in the sun?
    mrshroom2
    Community Answer
    I wouldn't recommend it. Polyurethane tends to become rather sticky when drying in sun light, leading it to collect any particles blowing around. Apply it in a well ventilated area inside without direct contact from the sun, and leave it to dry naturally, rather then trying to speed up the process.
  • Question
    Can I use a sander between coats, or should I do it by hand?
    Community Answer
    Yes, you can use a sander. A hand sander is best, but avoid using too much pressure. Aall you want to do is scuff up the surface before re-applying.
  • Question
    When applying poly for baseboards, do I need to be so fussy in sanding in between coats?
    Community Answer
    Sanding between coats is to make the new poly coat adhere better to the previous one for protection, not merely to make a clean, even look.
  • Question
    Should you apply a clear stain for a light table before finishing with polyurethane?
    Community Answer
    If you want to enhance the look of the wood, then yes. If you are okay with how it looks already, then no.
  • Question
    Can regular polyurethane be applied over poly-wipe?
    Community Answer
    Yes, poly-wipe is just a thinner solution of regular poly.
  • Question
    How do I apply polyurethane with a cloth?
    Community Answer
    Use a lint-free cloth such as an old, white T-shirt. Fold up the cloth to get a smooth 3-inch edge. Dip the cloth in the poly, let it soak in for few seconds and apply. It is better to apply a few thin coats over a few days, sanding lightly between coats, rather than one thick coat, which could cause an uneven look.
  • Question
    Which poly is stronger and more durable?
    mrshroom2
    Community Answer
    Generally you get what you pay for. Ronseal is a good affordable brand, with products like TekDur to be well worth the extra few pounds.
  • Question
    How do I prevent bubbles from forming on the surface when using water-based poly?
    Community Answer
    Stir it gently, don't shake the can, apply light coats, use a high-quality brush, use gentle brush strokes and go with the grain.
  • Question
    Can I use polyurethane after painting?
    Community Answer
    Yes, you can. Just make sure the paint is fully dried prior to applying the polyurethane.
  • Question
    Can I apply sanding sealer before I apply polyurethane?
    mrshroom2
    Community Answer
    Yes. This is, in fact, the best option for using any polyurethane varnish. Make sure you sand the sealer back using nothing less then 120 grit, so no white shows in the grain.
  • Question
    If I like the look of my cedar poles, can I just apply polyurethane without any stain?
    Community Answer
    Yes, you can. It's even easier without stain because you don't have to worry about sanding it off by mistake.
  • Question
    Can I apply polyurethane over and already polished/finished wood tabletop without sanding it first?
    Community Answer
    Don’t do it. It will just peel and chip. See the other Q and A about using a fine grit sandpaper to make each coat of poly adhere well.
  • Question
    Can I use polyurethane on my outdoor porch?
    Community Answer
    Yes, as long as the area is well ventilated, out of direct sunlight, and clean of any debris that may get blown into the drying poly and affect your final result.
  • Question
    Can I use for polyurethane for window frames?
    Community Answer
    You can. For this application, you will want to wipe the poly onto the surface. If the poly is water-based, rinse your lint-free rag in water prior to applying. If it is oil-based, dip the rag in mineral spirits.
  • Question
    If my final coat has brush marks or imperfections, how do I finish it to achieve a smooth end result?
    mrshroom2
    Community Answer
    Give it a gentle go with some fine sandpaper -- 320 grit or even 240 will do. Just be very gentle and make sure you sand evenly; otherwise, patches will appear.
  • Question
    Can I apply the polyurethane onto an oil-based stained wood?
    Community Answer
    Yes, it works nicely. The stain must be completely dry before adding the polyurethane.
  • Question
    How warm does it have to be to apply polyurethane?
    Community Answer
    There is no specific temperature but keep the object you are working on in a ventilated area out of direct contact with the sun.
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