[ rosette making ]The rosette serves no acoustic purpose, but it is one of the most subtle and complicated of all woodworking decorations. Particularly in England and in Italy, mosaic blocks were used as decorations for wooden objects long before guitar makers started to employ the same techniques to make their rosettes. In England this style was known as "Tunbridge Ware". During the late 1700s, many people visited the natural springs round Tunbridge Wells.
The local people started to make souvenirs for this new tourist trade in the form of small wooden objects, like trays, candle sticks, boxes and so on. As time went on, the level of skill improved to the extent that by around 1820, items could be bought with many different scenes assembled in wooden mosaics. Some of these were local views, but others were scenes from far afield. Such scenes took thousands of mosaic squares each one around 1mm square, to produce their pattern, like pixels on a computer screen. This may sound small, but on the scale of a guitar rosette, it is quite large!
I typically use a mosaic size of about 0.5 mm to give very fine patterns that trick the eye into seeing curves. However, the process is almost identical to the work that was carried out near London over 150 years ago.
- The pattern is worked out in squares on graph paper.
- A block is made for every vertical line of this pattern. I call these "bookblocks" because the lines are stacked horizontally in order, like the pages of a book.
- A vertical cut is taken through each bookblock, giving a line of tiny squares that is already in sequence.
- Tunbridge Ware was always rectilinear, so the "squares" were truly square. A guitar rosette however, has to run round the circular soundhole, so each strip is tapered slightly and glued into a finished shaped block. A number of blocks can be glued together to make a hollow tube.
- The pattern now runs right through the tube, from end to end. This can be sliced across from side to side to make thin "tiles" of mosaic. Each tile is identical. Bandings Bandings are the lines of thin wood that surround the mosaic. They can be plain or patterned.
- Diamond lozenges can be made by alternate block-making and cutting. In this case, an oblique cut is made through the pack of veneers. By choosing appropriate thicknesses, two of these strips can be matched together to make herringbone strips. Decorative lines and plain veneer lines can be assembled into a curved band. Tiles and bands are assembled together and set into the soundboard. Typically, a finished rosette is around 1 to 1.5 mm thick.