As a somewhat amateur pianist, I rely on our experts :
A friend entrusted me with his Yamaha U3; according to the serial number, it seems to date back to 1959.
I expressly asked him to entrust it to me because it is in a rehearsal room, like a lamb among wolves, with temperatures and humidity levels that are not very suitable. And it is not being played.
Testing it and finding it (in my very modest opinion) decent, I noticed that the soundboard appears to be varnished, and it doesn't look like such a light varnish.
Not having experience in this matter, my question is the following: is it common to varnish the soundboard? Was there usually a varnish present on that model? For what purpose?
Could it have been added later?
Very curious, I thank you in advance if you would like to give me your impressions
All soundboards have a special transparent coating. It is a very elastic varnish. In the factory, the seasoning of the boards occurs naturally for a certain period, then, the humidity level is artificially lowered to a certain percentage, I don't want to be wrong, between 10 and 8%. The thus "seasoned" board is "locked" with special varnish. Preemptively, the board is given what is called the "crown," that is, that bulge, that curvature that will allow it to withstand the pressure of the bridges. On the back, it is reinforced with slats of the same spruce called "ribs."
I have described in broad terms a procedure that every manufacturing House carries out according to its own design "philosophy."
Thank you Maestro, if I can, I will post some photos of the upright (as soon as it arrives home) for further clarification.
P
Pianoaccordatore
Reply 4 by Pianoaccordatore
I am also adding my contribution...
The soundboard is obtained by placing side by side and gluing together several spruce planks obtained from the trunk according to the quarter-sawing method.
After very strict selection processes (only a minimal part of this precious wood proves suitable for making the soundboard. Indeed, the creation of resonant membranes requires woods with high elasticity and toughness, low specific gravity, and absolute regularity and linearity of the grain), the planks are appropriately chosen and juxtaposed one next to the other.
Then the sides are planed and the gluing takes place. Once gluing is finished, the board is shaped by removing the excess. Subsequently, it is leveled and sanded on both sides.
The soundboard is finally left to rest for a period of no less than 3 years in a chamber that maintains strictly constant humidity and temperature conditions.
