Sanding or polishing wood too smooth... long
John Cotten, Harrodsburg, KY
>I have been reading for some time some of the posts regarding the level some people are taking their wood with sanding on the lathe, and just thought I would bring up a point which I am sure is going to make for some argument.
I rarely sand past 320. On occassion 400, and most of the time 280 grit. When you sand to the point of going to 1000, 2000 or above, you polish/burnish the wood to the point you frequently close off the cells of the wood, or fill them with enough microdust that you have a polished surface.
While in the near time, it produces a beautiful finish initally, most finishes will not bond properly with the cells full or closed off at this level of polish. The wood needs some porosity for the finish to adhere properly to the wood. I typically use a good sanding sealer, then lacquer to the desired level, or use oil and wax depending on the intended use. I have some turning that were done by Rude Osolnik 20 years ago and the finish has begun to haze and come off. I have a few I did some years back where the finish has had some problems. Using a jewelers loop, in both cases it was from the wood being over polished and the cells of the wood being filled to the point the finish did not bond well.
My point is, while it makes a beautiful finish polishing the wood, or burnishing would be a more accurate statement, over sanding will eventually lead to finish failure. It is better to buff out a oil or lacquer finish with a few coats to a glass smooth surface rather than burnishing the wood to achieve the glass smooth feel and look.
We woodturners are a fairly impatient lot when we really come down to it, that is one of reasons we turn, we can finish a piece in minutes or a couple of hours easily, but we are trying with the use of friction polishes and other similar processes to shortcut the finishing process, which if we look at classic case work, frankly takes time and patients have proper outcome.
I know there are those who will argue this point, but it is just an observation after nearly 34 years of turning.