Rosette Construction with a Spanish Method – Part I “The Rosette Log”
Designing and constructing a rosette is one of the most enjoyable tasks in making a classical guitar. There are a few different methods of construction when making this decorative ring around the soundhole. I have chosen to use the Spanish method. This technique is done entirely by hand and is aesthetically centered around repetitive pattern and movement. The aesthetic purpose of a rosette is to draw the observer closer to the guitar. Up close the detail of the pattern marquetry comes to life. As one moves further away, the small details blend together creating optical illusions.
A typical Spanish rosette is made up of three main fields, an outer ring, a center field, and an inner ring. These fields are separated by thin contrasting lines. The center field is where a guitar maker gets to design a mosaic-tiled pattern. The outer and inner rings tend to hold a pattern that enforced visual movement that leads the eye around the circle.
Rosette Detail
The rosette is not just a canvas for a guitar maker’s creativity, it has great structural purpose. It protects and seals the wood grain around the hole. A hole in a straight grained piece of spruce is very weak leaving exposed and changing wood grain. Without it the wood around the hole would be prone to cracking. The rosette is very important for adding stiffness and support back into a weak area of the top.
The Spanish method of constructing a rosette is centered around the use of hand tools. Most of my work on the guitar is done by hand with a lot of tools that I have made myself. Making the rosette by hand, instead of with a machine router or a fly cutter, is a method that I enjoy because it allows me to have more fun while getting more connected with the instrument.
Method
The first step is designing the mosaic tile pattern. The mosaic tile is made from cutting the cross section of a laminated log made from small strips of square veneer strips. It can be original or as complicated as you want, mixing different size tiles and changing the orientations. Once a pattern is decided, break it up into vertical sections. If the finished tile is ten squares wide you will have ten rows of stacked tiles. I detail this out in a diagram so that there is a reference to check the glue ups to make sure they are in order. Then, veneer strips are cut with a purfling cutter held against an edge so that each strip is the same width, about 2.5 mm (You could also use a ruler and a knife). The extra thickness makes it easier to glue up. Once all the strips are cut, group them together so that each row is complete.
Veneer strips grouped for each row
I use yellow glue for the rosette build because water is your friend. Thin the glue and apply it to one row of veneer strips at a time. It is messy and I find it very useful to do this part by a sink. Once the row stack is made you can wipe it down with a wet papertowl. I wax one of the walls of my shooting board and press the glued row up against it with a heavy straight edge. By the time I am gluing the next row and ready to let it set, the other one is dry. Glueing the strips in about 12″ lengths gives enough for two 6″ rosette logs.
Veneer row being pressed against waxed shooting board
All rows after glue has set
Once the veneer rows are dry, they need to be thinned so that the thickness of each row is the same as the thickness of the veneer used. This will result in having square tiles in the finished log. I start with a 102 handplane to remove most of the thickness then witch to a home made thickness scraper similar to one that I saw Eugene Clark use. The rows are pulled through, slightly tapping the blade each time, thinning the piece with each draw.
Rows being thinned with homemade steel scraper plane
Thinned rows and shavings
After the veneer rows are thinned they are cut in half and are ready to be glued. After making sure they are in order with your pattern you are ready for glue. I have seen some guitar makers use round molds and cauls to taper the tiles but I glue them up as I did the rows, nothing but thinned glue and hand pressure. The idea is that you want the same amount of clamping pressure every time so that you have consistency in all your tiles. When the tiles are inlayed, the glue can be used to soften the tiles and they can be negotiated and squeezed into position with an awl or the butt end of a wooden tool handle. Once the tile log is dry, they can be cut into 2mm slices and put aside waiting to be inlayed into the rosette.
Rows cut in half
Rows after glue up. Begin to see cross section pattern
Rosette Log cut into tiles
As mentioned- visual, protect
Rosette Construction will continue in Part II
Please don’t take this as negative criticism, your work is excellent. I doubt the rational given for rosettes. First of all , they are little pieces of wood held together edge to edge with glue. Take a piece of spruce and tap it til it snaps. Now take a rosette and snap it til, oops it broke of its own weight. dang it. how could that rosette hold anything together. Centuries before the modern sound hole surrounding rosette guitars had purfling around soundholes filled with parchment/wood rosettes. The purfling may have helped prevent cracking, but really trying to keep wood from doing what it wants to do is a fools errand. I suspect Spanish rosettes are decorative more than anything. If one wanted to strengthen the sound hole edges do what I do, glue secondary piece of spruce under the sound hole and cut though them both. On the other hand I am wrong about 75% of the time, so keep on being you, fantastic.
Thanks for your comment John! Most rosettes are constructed with both multiple single piece lines as well as a decorative pattern. Always a balance of form and function!