A well maintained instrument should be also outwardly recognizable. A lacquer finish with modern synthetic resin or other lacquers is not acceptable for a master-instrument, because no varnish withstands permanently the hand sweat and emerges at the edges of the tone-holes after short time. Besides lacquers smear the fine, carefully made profiles on baroque instruments.
You receive the most beautiful surface with a linseed oil matt finish. The instrument must be abraded first with a big peace of fine steel-wool (Rakso - 00 or 000). Wood will become thereby hardly attacked, brass rings become beautifully bright, only with polished ivory -, bone- or plastic-rings You should be careful. Subsequently, with a rag linseed oil is fully brought on the surface. After one day, not later, drawn in remainders of the linseed oil with a rag. After some weeks, the oil film is hardened and the process can be repeated whenever it appears necessary. The in such a way treated instrument gets a pleasantly feeling surface and after some years during influence of light by oxidation the beautiful brown-yellow colour, which is known from the originals in the museums.
On the hardened linseed oil layer you can apply a shellac matt finish if You want. Take some shellac on a cotton rag and rub thereby on the surface until it is completely dry. After some repetitions smooth ist again with finest steel-wool.