This is more likely to happen in woods with short, crotch or quilted grains and soft woods. Remember, sand lightly between Brush the sanded area off with a soft cloth to remove all traces of dirt and grit from the sanding. percent with solvent. Usually 6-12 hours later, start the process of applying the next five coats. brush marks will not have enough time to flow out. Finishes like Minwax Wipe-On Poly are just thinned varnish that will flow easily. the can and this will make the solvent evaporate much quicker. It dries fast so you can apply three coats in a day. When you apply a finish by brush, you are basically The first coat I use to seal the pores and raise the grain. The only solution I have found is to wet sand after dry. I usually have problems with runs, sags, and brush marks, so I'm pretty nervous about the polyurethane. level because of the extra solvent you added to the finish. Apply the polyurethane finish lightly to the brush… thickening too quickly. Therefore, you Viscous finishes like typical oil varnishes don’t flow easily, so brush marks can result. Applying polyurethane (and most other finishes) in heavy coats creates bubbles, puddles and runs and becomes a defect in and of itself. Realize that it’s only three days start to finish. will not burst all the bubbles, but don't worry, the remaining bubbles will burst and Wipe it off. Do not worry about sanding through the finish. And don’t drag the brush on the edge of the can. Water-base finishes must be applied with synthetic bristles. I do address this problem in the article I have on my Once the whole surface creating air bubbles. Apply the first coat of polyurethane using the best technique for the surface. Another point is the temperature of the air where you are varnishing. finish has enough solvent in it. Even though I’ve built dozens of cabinets and furniture pieces, I don’t consider myself a high-end finisher. get thicker because as the amount of finish gets lower in the can, the more air stays in A light coating of finish after sanding disguises the area. What am I doing wrong?—Jim Seroskie. Just dip the brush in and let it drain. Fabulon is a very good finish also. But I’ve developed my own little collection of tips, systems and techniques for applying oil-based polyurethane. I’ve been happy with everything from pure poly at Home Depot (ok), Rockler’s General Finishes with some linseed oil, (wonderful) or Daly’s Profin, similar oil base (fantastic). new and it's the first time you have opened it, but each time you use the finish, it will Richard Oedel replies: You aren’t doing anything wrong. Proper brushing technique will reduce the amount of air bubbles that develop in the Do all the scuff work with a firm gentle hand. If you cut through the finish, repeat third coat process. Well wiped down, you will find nearly no dust sticking. The second coat might need light sanding with 180 before the third coat. Brush flat surfaces with a thin coat using a bristle brush. At about coat 5, it starts to take on that satin sheen your are looking for. Bob LaCivita replies: Applying a brush finish is difficult with polyurethane or varnish. The only drawback is that when the finish dries and all the solvent has There are two main factors that cause a finish to bubble and show brush marks after it The first has to do directly with the way you apply the finish, (your brushing When brushing on the finish, make sure to load the brush enough so you can apply a The bubbles will not have enough time to pop and any Allow it to get slightly tacky, usually not more than 10 minutes. will have to apply a few more coats than you would have if you used the finish without bubbles will have enough time to burst before the finish sets up. have brushed on to their project. Rub the excess off quickly with a dry rag. Wipe contoured surfaces with a clean cloth, going with the grain. An above average finish brush is very dense and soft. Make sure your project is sanded well up to 220 grit or a little higher. have enough time to level itself. However, I do realize that some readers do not evaporated, less of the resin (finish itself) will be left on the surface. When you wipe off the finish, you are actually not wiping off the finish, but rather leaving a very thin film behind. You don’t need several different types of finish for satin or semi-gloss. Wipe on a thin coat over the whole project. The third coat is the tricky one. Thinning this much may not be necessary when the can is brand So you need many layers of finish to build up before you see the results. Do one surface at a time. Tipping off is done by wiping the excess varnish on your brush on the side of the small container then lightly drawing the brush, held perpendicular to the surface, and then removing the excess back into the can or to areas not yet varnished. Run tests on scrap panels until you get the feel. After stirring the varnish I always transfer a small amount to another smaller container to prevent any dust ot dirt from getting back in the original container. This slightly overlapping each brush stroke. Dipping it in 3/8˝ to 1/2˝ . You need to apply a layer that has a wet surface appearance, but not so much that it runs. It keeps moisture from damaging the wood. It's best to apply polyurethane to flat (as in level) surfaces so the finish can self-level and is less likely to drip. only to wind up with brush marks and or bubbles in the finish they This is a skip-the-brush system. Lightly touch the surface with the loaded brush and then start to move the brush across Thinning the finish will make it flow out better so brush marks will level and air I generally also sweep the entire area also. thinning it. When dry, scuff sand with 220 grit. Whether it be brush-on or wipe-on, I really love a good polyurethane finish. You will need at least three coats, but it dries fast. Let dry 24 hrs. Urethane and varnish hold up where oil finishes and shellacs fail. Apply more varnish on those areas. It gives me great results, quickly and painlessly. Try not to overload the brush, because When brushing on the finish, make sure to load the brush enough so you can apply a liberal amount of finish without having to press down on the brush to get more out. This is absolutely incorrect. Even though I’ve built dozens of cabinets and furniture pieces, I don’t consider myself a high-end finisher. 8-12 hours later, feel the surface.