Once the fret work is complete, the bouzouki can be finished. The quality of the finish achieved will only be as good as the quality of the preparation work. The entire instrument (minus the fretboard and frets) must first be sanded. Start with 100 grit paper, and work up to 400 grit paper. Then the pores of the wood must be filled. Many luthiers leave out this important step, and the finish on their instruments shows it. After filling, the instrument is lightly sanded again, and then it is ready for the finish to be applied.
There are a variety of finishes on the market, and each has their pros and cons. I use KTM-9 waterborne finish, because it is easy to apply and environmentally friendly. It can be sprayed with a regular compressor or an HVLP sprayer or it can be brushed on. Clean up is with soap and water. After the finish is applied, the finish must cure. Hang the instrument in a warm room with good air circulation, and allow the finish to cure for two weeks. After curing, the finish is leveled with sandpaper starting at 400 grit and working up to 1500 grit. It is then buffed with three different grades of buffing compound on three separate cloth buffs on a buffing machine.