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Wet Sanding the Guitar Finish

Sorry that it’s taken a few weeks to post here, but as you may well be aware, building coats of lacquer on the face of a guitar body is an arduous and time consuming process.  For the past few weeks, my life has revolved around “spray a coat of lacquer on one side of the guitar and wait an hour”.  After spraying many coats of lacquer on one side, I would get bored and want to work on another side.  Of course, one must let the coats of lacquer dry for at least 24 hours before you can flip the guitar body, and place that side down (against the work surface).  The goal in this step is to build the surface of the lacquer high enough so that you can sand it to a smooth surface, and finish (while retaining a thick protective coat of lacquer).  Overall, I believe I am on my tenth can of Krylon Spray Lacquer.

As a side note, a friend of mine who is quite experienced in building guitars (starting with nothing but a solid block of wood, mind you, and is infinitely more experienced than I) has recommended that I use “nitrocellulose lacquer”, should I ever decide to take on another guitar project (rather than the acrylic lacquer that I’ve been building).  Apparently, nitrocellulose lacquer layers MUCH more quickly, and expands much more than acrylic lacquer to allow this step to be completed in less than half the time.  Also, it is supposed to be much easier to sand nitrocellulose lacquer.  Since I’ve already started with acrylic lacquer, however, I have to keep going as it wouldn’t be prudent to mix and match different types of finish.

The above picture shows what the surface of the guitar body looks like, after building about ten coats of lacquer.  You can see many waves, and imperfections directly on the surface of the guitar.  The sparkle, however, shows through very clearly and impressively.  My friend, the guitar builder, has recommended that I “wet sand” the surface of the guitar at this point.  The reason for this is to smooth the surface, so when I am building the coats of lacquer, they will apply more smoothly.  The only caveat is that I MUST be careful not to sand through to the aluminum flake layer beneath the surface.

The two pictures, above, are more views of the face of the guitar.  These aren’t as bad as the first, but again, you can still see imperfections in the surface of the lacquer.

The process of wet sanding involves using a fine, 400 grit, wet sanding paper to smooth the surface of the lacquer.  I had to purchase this paper from a local automotive paint store, as it is too “specialized” a product to be carried at the local Home Depot or Lowes.  Once you have this sandpaper, simply dip your fingers in a little bowl of water, drip it on the surface of the guitar in the area in which you intend to work, and lightly sand.  There are a few things to keep in mind during this step:

  1. You must allow your last lacquer coat to dry for at least 24 hours before attempting to sand.
  2. If the lacquer curls off of the surface into tiny little lacquer balls, then you must stop and allow it to further dry.
  3. If the surface of the lacquer has dried properly, then sanding should produce a result similar to what you see in the above picture.

The above picture is a top-down view of what the surface of the guitar looks like after being wet sanded.  Please note that I tried my first pass in an area that wouldn’t be conspicuous in the final product.  This area would be fully covered by the pick guard, and would be concealed if I had made any fatal errors!

The first impression you have after looking at a fully sanded guitar surface may be one of panic.  After all, you’ve just scuffed the entire surface you’ve worked so hard on carefully building!  Fear not, as lacquer is somewhat of a miracle sealant.  The way lacquer works, is that when you spray a coat of lacquer on top of an existing coat, the lacquer “melts” the existing surface, and then fully bonds with it.  This way, you produce one CONTINUOUS coat of lacquer, rather than successive individual coats as you would with layers of paint.

Before you spray a coat of lacquer on your sanded surface, you must be sure to wipe it down with a good tack cloth.  This will pull any sanding dust or debris from the surface of the guitar and give you a clean surface with which to work.  The above picture is what the guitar looks like after the application of a single coat of lacquer after sanding the entire body.  Not only is the face of the guitar MUCH more smooth, but the black sparkle is beginning to take on a much more rich appearance!  Keep in mind that further applications of lacquer will completely eliminate all trace of the sanded surface and restore the guitar to the smooth, clear, appearance.

That’s all for now, and it may be a few weeks before I post again, so enjoy.  As always, let me know if you have any questions, comments or suggestions!

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