MAKING YOUR OWN ROSETTES
By Bill Lewis
When a little old lady looks at a fine rosette, the comments go something like the following:
"Oh, my, isn't that lovely! Like petit point, only finer. How's it done? Is it a decal? Or paint?"
"No, Ma'am, it's all wood."
"You mean little pieces of wood? All those little pieces of wood? Oh, my, how could anyone do all that?"
At this point, the little old lady is seeing pictures of someone with powerful magnifying glasses and fine tweezers placing, one after another and with infinite care, microscopic pieces of colored wood.
From this view of mosaic making (which I refer to as the "little old lady" approach), spring some of the fantastically difficult and time consuming methods in use by many amateur and even some professional builders.
For many years, Spanish luthiers have been using a fairly simple and "mechanical" system for the production of mosaics. There are variants of this system with certain details handled one way or another, but the basic process is fairly universal.
My own opinion is that mosaic making is not really necessary to classic guitar building. It is a frill for those who like fine work and have time to spend on decoration. If you have time and enjoy making designs, it's a fun thing to do; otherwise, buy one already made.
Dive To Bottom
Decide on the following factors:
(1) Width (c)
The above four factors are general in nature and will have a far greater effect on the overall appearance of your guitar than the actual design. Think carefully about what you are trying to achieve in the instrument's total appearance. Is it enhanced by the type of mosaic you envisage? It's the whole Instrument that counts. The fine details of the design will seldom be noticed. The point is, don't get so caught up in the specific pattern that you forget the general appearance.
Now, lay out the outside rings. In most cases, these will be black, or at least very dark. Since you will be working with veneer about 1/28" thick (as a rule), you could lay out 2 to 4 1/28" black rings. These would normally be reflected equally in the inner rings.
Next, some rings of another, lighter color as planned, then more black. Work it out to suit your own taste. For the first attempt, I would suggest that you keep the size of the mosaic tile center down to 1/4" or 3/8" as it is harder to handle when it is larger. So, if you end up with inner and outer rings of 3/16" each and a mosaic tile center of 3/8" making a 3/4" mosaic (3/16"+3/16"+318"=3/4"), you should be O.K. Examine the rosette photographs on the previous page.
Although it varies with different makers, I would suggest a symmetrical (mirror image) relationship between the inner and outer rings. I prefer it and I suspect you will, too.
THE BUILDING PROCESS
The mosaic (center) is made up of blocks (or tiles) which are fitted together in a certain way to form a continuous, complex design through the center of the rosette.
Graph paper and colored pencils are very helpful in designing the tiles. You can save 50% of your tile making labors by realizing that they may be turned over to obtain a mirror image and that individual sections of tiles often duplicate other sec- tions. Here's an example of a mosaic layout:
Observe that lines a & c, and lines h, i, & j are identical. So that, out of an 11 line tile, there are only 8 different lines. With careful designing, this can be reduced.
Also, if face 1 is always placed against face 1 in the adjacent blocks and likewise, face 2 placed against face 2, we now have a 22 line mosaic of considerable complexity. It could easily be simplified by deleting, for example, lines a, b, and c.
I would suggest that your first mosaic be much simpler than the above example. It is quite possible to make a very attractive mosaic with only 3 different lines of 6 rows.
Here is a more extended view of the above design including the rings:
You should now have a design drawn in color from which you can begin to build up the parts for the mosaic. Make an inventory of what lines will be needed. For the example above, you would need:
In this example, we will plan for about 20 rosettes. You can scale down, if you wish, but it's nice to have partly finished tiles of your own design if you plan to continue building -- your luthier's signature, so to speak.
Colored veneer is then cut into strips of, say, 1"x 6" or 1/2"x 6" if fewer mosaics are required. For a large, complex mosaic like the above, many pieces will be required. The veneer can be cut with a sharp stripping knife guided by a rubber or cork backed steel ruler.
The pieces are then laid out in the order of each line. In line a, for example, two sandwiches are made up as shown (or a double sized one to include line c). Put a rubber band around each sandwich to keep the pieces in order.
When all lines (a to k) have been made up, the above bundles are glued together with hide glue in a small jig made of plywood. If the jig is heavily waxed with beeswax and then a propane torch is used to spread and "burn in" the wax, the glue will not stick to the form.
This little clamping press will be used later on to make up the logs from which the final mosaics are cut. Also, it is a very useful tool to have around your workshop.
It is not necessary to wait until the hide glue is completely dry to remove the sandwich. Usually, depending somewhat on humidity, etc., 30 minutes or an hour is enough.
I would suggest that at this point, the excess glue on the outside be cleaned up. Ideally, very little glue should remain since the excess should have been cleaned off before the sandwich went into the press.
It should also be noted that more than one sandwich can be glued at a time, either side by side or one on top of the other. In the latter case, a spacer can be placed between the sandwiches.
All these variables depend upon the size, number, and speed required. Design your press according to your own needs. Make a good one if you like this type of work.
At this point, you should have a number of completed sandwiches each representing a line of the mosaic design drawing.
The next task is to cut up the sandwiches in order to make the line sections shown on the design drawing. This cutting can be done by hand with a fine-toothed backsaw, then planed or scraped to thickness. An easier way to do this cutting is to use a small circular saw with a blade of .015" to .025" in width. A blade taking a wider kerf will waste a great deal of valuable materiaI.
Some makers cut these strips squarely off the sandwich; others cut off wedge or pie shaped pieces to compensate for the curve of the rosette. The wedge principle is, of course, more precise but it is also more troublesome. Those who do not use it, compensate for it to a considerable extent by softening the glue when the whole mosaic is in place (in the guitar top) thereby letting the parts move around a little, spreading, and compressing and generally finding their own level. For your first mosaic - if it contains no more than 6 or 7 rows - I would suggest the simpler method, otherwise a slight wedging is in order.
A simple device for planing (scraping) these strips to precise thickness can be set up as follows (if they have been well sawed with a circular saw, they may not need further preparation):
All the strips are pulled through in the direction of the arrow with the blade set rather wide. Push the strip down into the blade then pull through, then turn the strip end for end and repeat. Gradually, tap the blade in after all the strips are thinned to a specific level and repeat until all the strips are smooth and planed to the desired thickness. If pie-shaped pieces are desired, cut an angle on the blade.
When all the strips are thinned, they are glued into a log (using the press), the cross-section of which is identical to the mosaic layout pattern. This log is laid up and produced in the same way that the previous sandwich was made. Don't let the clamp pressure force the log apart since the new glue will soften the old glue.
The logs are then carefully sawn into mosaics 1/16" to 1/8" in thickness (I suggest about 3/32") and are ready for laying in.
PUTTING THE ROSETTE TOGETHER
The following are two variations of the Spanish system:
This is the system used by the most dexterous makers. It begins with a top unthicknessed but roughly surfaced with a plane. The trough for the mosaic is cut, hollowed out nearly to the other side, and cleaned up.
Colored stripping is then set in ordered bundles for the inner and outer rings. Hide glue is then slopped into the section of trough which will be covered by the fingerboard. The ring bundles, tied together by thread at the one end, are pressed into the trough with the mosaic tile between them. More glue, more tile, more ring, on and on around the trough until you are back beneath the fingerboard again. Sounds like juggling but it's not so difficult; even I've done it.
The basic procedure is the same except that the mosaic tiles are replaced by a ring of white strips used as spacers. When the glue has partially dried, these spacers are removed and, with more glue, the tiles are set in their place.
In either of the above variations, fitting of the parts must be carefully checked or you will end up with one or two tiles in backwards for sure. Also, it must be remembered that the wooden parts will swell somewhat when the glue starts to soak them, so don't make a press fit when dry.
When the mosaic is finally in, you should smear glue all over the rosette a time or two to fill any little holes left by uncareful work or small misfits.
If the parts want to pop out or don't stay down in the trough, a sheet of plywood with foam and waxed paper can be used to clamp them down until the glue is dry.
The mosaic is now cleaned up with a very fine, sharp scraper and some fine, sharp sandpaper. With the sandpaper, avoid rubbing the dark sandings into the top, otherwise you will discolor it.
A FEW COMMENTS
If you find, while gluing, that the combination of the rings and the tiles is too large or too small, remove or add black edge strips to bring it to the correct size.
By wetting the tiles and rings in the trough with glue, they can be shifted around enough to improve a poor fit. The parts should be wet enough to wiggle a bit but dry enough to stay together somewhat.
So there you go. Allow about six to eight hours for designing and making the mosaic tiles. It's for fun - not profit.
Bill Lewis is former owner of Lewis Luthier Supplies of Vancouver Canada. About 12 years ago, we took over the business and moved it down to the States. Bill is involved full time as a professional photographer and often has exhibits In the Vancouver area.
Text From The Luthiers' Mercantile Catalog - 1993
Previous | Next | Top | Construction Tutorials | Home
- 9.10 -