I’m assuming with this post that you have completed all the operations of your guitar and all assembly procedures have been competed. the frets are installed and finished, and everything but the bridge has been installed.
Note: Prior to finishing the guitar, you do not want the acoustic guitar bridge installed, but you do wish to install the classical guitar bridge. The acoustic guitar bridge location should be marked and masked off so no finish is applied to this area.
A word of warning here. Do not sand your guitar with a sandpaper that is finer than grit 220. This will make the wood surface too slick and your finish may not adhere as it should.
Be sure that there are no sharp edges on any surfaces as our finish will not adhere all that well to a sharp edge. All edges should have a radius edge. This is true for the purfling edges, fretboard edges, headpiece perimeter and any neck edges. For purflings, I prefer to have a radius of about 1/16″ or more as this not only assures good finish adhesion, it provides comfort for the guitar user. For the remainder of the edges, just knocking off the sharp edge is enough.
Clean Exotic Woods:
If you have used any exotic woods that contain waxy resins, be sure to completely clean all exotic wood surfaces with Acetone and a clean cotton cloth. Thoroughly wipe down surfaces until you see no more colored residue on the rag. You may find that some of the white purfling lines have taken on some of the coloration of the exotic wood during this process.
This takes a bit of work. You should take a very sharp, small metal scraper and carefully scrape all of these purfling lines to take just the coloration off the purfling.
GLS Tip: As we have noted to you very exhaustively, the use of Acetone if very dangerous. It is both flammable and can be soaked up by your skin. Be sure to practice caution with this product and use rubber gloves, a very good respirator and take care not to use near a flame or any spark.
Cleaning Plastic Bindings:
Again if you use the Acetone cleaning process above and you have plastic purflings on your guitar, you will need to scrape the bindings of the guitar, I chose to do this with a a mini-scraper as shown in the photo at the top of this article. It consists of a utility knife blade attached to a depth stop consisting of a slotted dowel. By adjusting the amount the blade protrudes through the dowel, you can control the depth of scraping so as not to dig into the guitar wood below the binding.
Once the depth is set, securely wrap the end of the dowel with filament tape to lock the blade into location. You could also choose to fabricate a custom scraper whereby you could adjust the depth of cut and more secure locking of the blade. We will cover that in an upcoming article.