Expert's Corner — finished
Finishing Tips by Bob Flexner: Sanding
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When sanding wood in preparation for a stain or finish, you need to remove all the problems in the wood – mill marks, tear outs, gouges, etc. – with the coarsest grit sandpaper you’re using before moving on to finer grits (to remove the coarse-grit scratches). This means that the coarse-grit sandpaper you begin with should be able to remove the problems quickly and efficiently to reduce the amount of work required. On the other hand, with factory pre-sanded veneered plywood or mdf, beginning with 150-grit sandpaper is usually adequate.As an example, 100- or 120-grit sandpaper is usually coarse enough...
TIP: Dealing with Bubbles in a Finish
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Bubbles in a finish are more likely from brushing than from spraying, though it’s possible to get bubbles in a sprayed finish if you have the air pressure turned up real high. Bubbles are caused by the turbulence created by the brush gliding over the surface much more than from shaking or stirring the finish. The problem is worse if your shop is hot or if the finish and wood are at different temperatures. Because some formulations bubble less than others, especially with varnishes and water-based finishes, you can also switch to another brand, which may reduce the problem. To...
TIP: Spraying Outside
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One solution for spraying your project when you don’t have a spray booth or adequate exhaust in you shop is to spray outside. There are some conditions, however, for getting good results. First, you need to pick a day with temperatures in the high sixties to low eighties. Colder will cause the finish to take much longer to dry and this will create more time for debris and bugs to land on and stick to the finish. Hotter will cause the finish to dry too fast, which may lead to dry spray—the finish drying before it lands on the object....
DEALING WITH THE CHERRY BLOTCHING PROBLEM
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Cherry was long thought of as the poor man’s mahogany and was used as a substitute for mahogany. But as quality mahogany has become harder to get, cherry has become increasing popular and is now widely thought of as a quality wood in its own right. Though cherry has a beautiful color and is easy to work, it is difficult to finish nicely because of its tendency to blotch. Blotching is uneven coloring caused especially by stains, but also by just a clear finish, that leaves some areas darker than others. Everyone wants to know how to avoid blotching in...