Neck sizes can vary, even on relatively recent instruments. So a thorough evaluation of the instrument is of paramount importance before we commit ourselves to the modification. First we check whether the topmost part of the neck is a minimum of 23.5mm wide. The thickness should be a minimum of 18.5mm at the thinnest part, and 19.5mm at the thickest. If these basic prerequisites are met, we know we can add to the original neck without dramatically altering it.
As to the choice of wood for a structurally vital part: end-grain joints tend to be problematic, and many restorers refrain from using them with reason. I try not to use that kind of wood either.
1. Once the fingerboard is removed, extreme care must be taken while detaching the neck from the main body with a sharp knife. In this case I had to use a saw to cut the pins used by the original luthier. Care and attention at this stage will be rewarded later, as by saving the majority of original parts the job will be made easier and cleaner.
2. Now the neck has been removed as well. In this example we can see the marks from a pair of wooden pins used to secure the neck. I have been fortunate in extracting the part cleanly and without damage to it or the main body. The pegholes have been bushed to be re-drilled later.
3. The next task is to glue the extra wood into place. In this case, for a violin neck, I have used a block 14.2mm long, measured from the end of the neck to the upper edge. I put extra care in selecting the right piece of wood, with a flame similar to the original, to make the supplement as inconspicuous as possible. The extra material will later be cut at an angle of 86 degrees.
4. Next I glue a further piece of wood to the button, to add the extra size needed there.
5. I add two more lateral pieces to complete the desired final measurements of the neck root. They also serve to secure the previously added pieces in place.
For this stage it is vital to seek out a piece of wood as similar as possible to the original, to make our restoration as invisible as possible. These sides of the neck will be immediately visible so I make sure they are just right visually as well as structurally.
6. One practical technique I have developed over the years involves adding two small angled pieces to the laterals before gluing them: they will compensate for the angle at which the sides are positioned, facilitating the task when placing them on a vice. If I don’t do this, they tend to slide out of place.
7. The parts have now been clamped in place. I try to put them into a vice immediately after the first clamp has been secured, thus allowing further control and liberating my hands from the inevitable drips of glue.
8. Now the new parts have been glued in place. As can be seen here (8a), the side parts add stability to the ensemble, also masking the added pieces. At this stage I also mark the final measurements for the neck root (8b).
9. I mark coordinates on the top plate for where the bridge will be positioned. I also add a mark on the lower bout (not visible in the photo) for the same reason.
10. At this point, the fingerboard is glued back on.
11. The final stages comprise carving the neck root to give it its final form. I simulate ageing of the parts with a personal recipe involving instant coffee, applied with a brush.
12. I use different varnishes according to the instrument in question, in this case the 1704 formula by Simone Fernando Sacconi, which adapts well and is easily applied. Then I polish the area, allowing for wear spots and applying dirt to the corners, to make it all look as if it has already been in use for decades.
TRANSLATION BY HERNÁN VILLAMIL.