Woodworking Tips
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Rubbing Out a Finish on Woodworking
I got a question about a technique called rubbing out a finish. I remember doing this to my car as a teenager, but I've never tried it on a piece of furniture. So I asked the guys at ShopNotes how it works.

The secret to getting a "perfect finish" isn't how you apply the finish, they said. It's what you do after the finish dries. That's where rubbing out the finish comes in. By removing flaws in the finish caused by dust particles or brush marks, it makes a finish feel smoother. And it improves the look of a finish by creating a nice even sheen (gloss or satin).

But before you get started, you need to build up the thickness of the finish. How thick? That depends on the finish and how much sanding you do between coats. They suggest five or six coats if you're going to use this technique.

Although it may be tempting to rub out the finish as soon as it dries, it's best to wait a while. By giving the finish time to harden (at least a week, but a month is better), you're more likely to get a uniform sheen.

When it's time to rub out a finish, the basic idea is simple. You use a series of progressively finer abrasives to create a pattern of tiny scratches -- just like sanding a board.

The size of these scratches determines how much light is reflected. So depending on where you stop in the process, you can get either a satin or gloss finish.

Regardless of the look they're after, they start by wet-sanding the finish with soapy water and 1000-grit silicon carbide sandpaper. A film of soapy water helps to keep the sandpaper from clogging. And a rubber sanding block ensures a flat surface.

The thing to watch is that you don't accidently cut through the finish. So check your progress frequently, and continue to sand until you get a dull uniform sheen.

Next, to bring out the satin sheen, switch to a powdered abrasive called pumice. Here again, use soapy water and sprinkle on the pumice (they say a salt shaker makes a handy applicator). Use a felt block to rub the pumice evenly across the surface, and then wipe it off.

After you've wiped off the remaining pumice and checked for a consistent sheen, you may want to use rottenstone to rub the finish to a high gloss. It's applied the same way. But it makes smaller scratches that create a shinier surface.

Finally, to get a mirror like surface, you can apply a polishing compound and buff it out. Pumice, rottenstone, felt blocks, and rubbing compound are available at woodworking stores and from mail order sources.

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