Delete anything left of the old finish. There are two ways to do this by using either a chemical stripper or sandpaper. The first method uses highly toxic chemicals and can damage parts of your guitar. The second method is much more labor intensive and also requires some practice in the right way.
Lightly sand the guitar’s rich wood. If this is not done, the new finish you are able to hold will not stick and will flake off. Even if the raw wood is exposed, you can use wood bleach to correct any stains that may have been inaccessible while the finish was still on the guitar.
If the guitar is made of porous wood (as many guitars were) use a filler, such as epoxy or acrylic varnish, to fill in the most prominent pores. Sand the filled pores to ensure that the filler is smoothed down.
Select the desired finish. Each guitar is different and there are many different types of finishes. Classical guitars are often finished with a technique called French polishing, which means applying layers of shale mixed with alcohol and then using a few drops of oil to ‘polish’ the shell until the instrument surface is uniform (see references for more information). polishing takes time to master, you may want to use varnish or various synthetic materials that are easier to apply. If you are trying to restore it to its original condition, do not use a finishing technique after 1950.
Use masking tape to protect the guitar’s bridge and neck before refining. The neck is glued in the unfinished wood and should not come in contact with Finishing products should remain on the outside of the guitar.
Apply the base coat on the surface. This should be Shellac on an older guitar. When applying Shellac or other chemicals, do so in a ventilated room, as the vapors are toxic. After the base coat, apply a second and third coat with a water-based varnish. This can be done with a brush, but to prevent runs, spray on.
Replace the guitar after the targets have dried. Sand carefully and be careful not to damage the application of the surface. After this is done, continue applying the finish and sanding until the desired amount of coating has been achieved.
Tips and warnings
The guitars were a bit popular from the end of the 19th century through the beginning of the 20th century. Parlor guitars are easily recognizable, as their bodies are smaller than concert guitars. Various surfaces and forests were used to create these instruments — it was often more convenient than acoustic purposes.
Refinishing an old salon guitar is not much different than refining a modern acoustic concert guitar. However, it is still very difficult.