Simple repair of the guitar
If the guitar is seriously damaged it would be better to go to an expert, but simple repairs can be done by yourself with some patient and care.
In the most cases some suitable glue and wood clamps are all you need.
In the case of disruption of wood connections these can be glued. You need to pay attention to the fact that the parts that have to be connected are dry and clean, and fit exactly.
If the parts are covered properly with glue and pressed firmly in place the superfluous glue can be removed with a moist cloth.
In case of cracks its best to use bone glue in contrast to disruptions then its better to use normal white glue.
Bone glue can be obtained in powder form and can be used cold or hot. Hot bone glue will surf the best.
In case of a larger crack its recommendable to consolidate the crack from within the guitar with a piece of wood. This must happen via the soundhole. Attributes such as a torch and pincers are indispensable.
The crack itself can be rubbed with bone glue and further fixed with wood clamps until the glue is dry.
Deeper cracks will have to be filled with a special filler that can be obtained in a special store. The storekeeper can tell you more about the suitability of the filler for your guitar. Its recommendable to use a filler with a lighter colour than the wood you are going to treat, this way it will be easier to correct differences in colour afterwards.
To prevent lose of colour its necessary to treat the wood with more layers of lacquer or special sealer before you use the filler. Never apply a second layer of filler before the first one is completely dry.
Nowadays there are different kinds of synthetic lacquers available.
Traditional classical guitars will be polished, this gives a deep warm tint. A disadvantage of this way of treatment is the vulnerability.
With the choice of the lacquer one must pay attention that the tone of the guitar will not be affected negatively.
Your supplier can advise you to obtain the right lacquer.
Sometimes to compromise the sound-blade (the most important part of the guitar) will be treated with polish while the rest of the resonance-box will be treated with a synthetic lacquer.
Wood stain on turpentine base is very suitable for classical guitars.
For the beginner a wood stain on a oil base would be easier because it takes longer for this kind of stain to dry.
This in contrast with synthetic lacquers, these have to be used quickly.
Wood stain on oil basis could effect the high tones of the guitar.
The removal of old lacquer layers can be done in two ways depending on the lacquer.
One way is removing the lacquer with sandpaper. This can only be done with guitars that are treated with non-synthetic lacquers.
When you come closer to the wood while scouring use sandpaper with a grit of 340 to 400.
Always scour in the same direction. (along with the thread of the wood).
While scouring use finer and finer sandpaper up to 600 grit. Continue this action until the wood is clean and smooth. Finally remove fat from the wood with turpentine.
For the removal of synthetic lacquers a caustic agent special for wood will be needed.
If you are going to treat the sound-blade with a caustic agent be aware that no caustic agent gets in the resonance-box via the soundhole.