Monday, January 01, 2007

Sanding question

Here is a question I was recently asked, and always a good one, "at what grit should I stop sanding?" As in many a good question, the answer is, "it depends."
Assuming we are turning an art piece, a lot of the sanding need depends on wood and finish. Not all woods respond well to the same finish. Some woods like oak are very open pored and respond differently than say a maple with tighter pores.
As a rule of thumb, I like to sand higher for oil finishes than for coating finishes such as varnish or lacquer. For oil, on an open pored wood like oak or ash I would likely stop at 400 to 600 whereas on maple I would likely go to 2000. For varnishes or lacquers, I would tend to stop at around 240 or 320. In the case of finishers like this, you are adding a coat that needs a bondable surface. Too fine a surface does not help and may hinder a finish. That said, a varnished surface can itself be sanded to 2000 grit and takes on a real luster. The clear coat on a car body will likely be sanded to 2000 and makes the underlying paint come alive.
Any comments on other people's sanding preferences?

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