Final Sanding on a Varnished Guitar

Using fine sandpaper and polish for that glass-smooth finish. July 11, 2005

I finished a solid body guitar with Behlens rock hard table top varnish. It is ash with maple top. I thinned it and brushed the varnish on and wet sanded between coats. I put about a dozen coats on it. Now I am ready for the final finishing. How do I get the final coat smooth and the maximum gloss possible?

Forum Responses
(Finishing Forum)
From contributor J:
Sand it with 400 wet or dry sandpaper. Then sand it again with 600 wet until all of the orange peel is sanded smooth. The 400 gets out the orange peel and the 600 or higher gets out the 400 scratches. Then polish it with automotive polishing compound. There’s a good amount of labor, but the results are rewarding.

From contributor R:
Be very careful not to sand through a layer of varnish or you will get a halo that will be impossible to get out and have to put on another coat of finish. I like to use 3M micro finishing film in micron grits for wet sanding. With 20, 15, and then 9 micron, I find there is less chance of burning through a layer and the scratches polish out much quicker. I also like to use 2K poly or polyester because it eliminates the layer burn-through problem.