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II. Inlay Patterns, Layout, and Pearl Cutting
When last we met I spoke of tools and materials (in Part I of this series), and I left you staring at an array of scribes, jeweler’s saws, thin blades, and noisy high speed drills. Now, you must choose an instrument or other object to be inlaid, purchase some inlay material, and either purchase or design a pattern to cut. For your first effort, I suggest that you stay with mother of pearl from the pearl oyster, and save abalone for a later endeavor. The reasons are simple: abalone tends to be somewhat more brittle than pearl and most abalone is almost twice as costly as mother of pearl (or more). Mother of pearl and abalone blanks and laminates and other inlay materials are available from luthier supply companies and from specialty suppliers. I have my favorites among both types of merchants but I’ll leave it to you to develop your own. Many suppliers also sell machine cut inlays and some sell inlaid fingerboards and peghead overlays but that’s not why you’re here.
I have seen pearl advertised in thicknesses that range from 0.02 to 0.06 inches. Inlays less than 0.04” are usually pretty translucent and may not contrast well with wood. Use 0.04″ blanks for flat surfaces, and thicker material for curved surfaces, such as arched guitar fingerboards. Thick blanks are also less likely to break as they are cut. Thick blanks do increase the rate of blade breakage, so be sure to have an ample stock of medium blades available. Mother of pearl is sold by the piece or by unit weight, typically by the ounce. Many suppliers claim that one ounce is sufficient to cut a Gibson-style banjo neck, but I have found that although an ounce of thinner blanks will cut all of the fingerboard pieces it will not usually cut the peghead pieces (even though there are more thin than thick slabs to the ounce). Further, many peghead patterns require oversize blanks (e.g. Gibson Flying Eagle and Bella Voce), so if you have such special requirements be sure to discuss them with the supplier. Most suppliers do not “grade” mother of pearl (except to separate the “gold” pieces, which have a specialized market), because highly figured pieces are scarce enough so that the cost of sorting by hand would multiply the final cost of the pearl manyfold. The end-user should pick out the best blanks from any given batch and stash them away for some future ultimate inlay job. Look carefully at each blank and wet it to reveal unsuspected figure and color. Check both sides. Use as plain and routine a selection of pearl as possible for your first cutting efforts.
The inlay design is dictated by the nature of your project, and for this, you must choose carefully. I think that the best instrumental candidates for practice material are instruments you have built yourself or instrument necks you have built or purchased. You might consider a medium-priced commercial instrument, one that is unlikely ever to be collectable, but you will have to strip and refinish the peghead, de-fret and refret the fingerboard, etc, none of which is simple and all of which increases the likelihood of project failure on the heels of a successful first inlay job. I don’t recommend altering even these instruments, and please do not tamper with a fine or collectable instrument (don’t laugh—too many great instruments have been “customized” with misbegotten pearl inlays). Like many other aspiring inlay artisans, I started by inlaying a reproduction Gibson banjo neck. This is one of the best ways to learn because most of the “prewar” Gibson Mastertone patterns are relatively easy to cut, and there are enough pieces in most of the patterns to give you lots of practice in layout, cutting, and inlaying. Banjos are generally very amenable to such decoration–in my opinion too much pearl on a guitar or mandolin is too much pearl, but banjos rarely have this problem. The various Gibson, Vega, Paramount, and other inlay patterns are available from suppliers, and for your first effort you should probably stick to one of those (assuming you have a project that would use such a pattern). Select a pattern in keeping with the instrument–a 1920’s Gibson tenor banjo pattern would look pretty strange on a guitar neck. The best time to inlay a new fingerboard and peghead overlay on a new neck is after both are glued in place and the neck and peghead are profiled and bound and the binding has been leveled with the playing surface of the fingerboard, but before the peghead is reduced to final thickness and the neck is shaped. The squared unshaped neck back surface is much easier to control and any dings that happen during the inlay work will be removed when the neck is shaped. If a banjo neck is not part of your present or future world, you could also just inlay a box, a cribbage board, or something similar. The important thing is to get to work.
If you are more adventurous and want to design your own pattern, by all means do so. Get ideas from extant inlay patterns, Grecian urns and columns, $100 bills, TV test patterns, classic museum architecture, kitchen fixtures, chandelier displays, or deep within yourself, and draw them on a piece of translucent graph paper (I use Clearprint 100% rag vellum, 10 squares to the inch, which is available from art and graphics suppliers—megabucks but worth it). You can work within a delineated area the exact size of the surface to be inlayed, or you can draw much larger patterns to be reduced photographically or Xerographically to actual size. I work up script patterns (like my brand name) by writing with a medium-wide calligraphy pen until I have the pattern I like and that fits in the assigned space. Then I overlay a second sheet of translucent paper on the design and trace carefully around the edge of the script with a size‑0 technical pen or “crowquill” pen and India ink. Other types of patterns can be drawn in pencil, and then traced with the technical pen. If you design your first pattern, you will undoubtedly discover later as you are attempting to cut the pearl that not all designs can be cut. Try to remember as you design to keep straight lines straight, and curves as segments of a circle, rather than as ovals. Remember that you will not appreciate your design fully until it is embedded in the wood, after it is much too late to change it, so try to keep it simple and elegant, especially the first time out.
Lay out the pearl slabs on a table and examine each one to determine the best side. Take your purchased or drawn pattern, make sure you have lots of accurate photocopies, and with scissors cut out the individual designs. I number each piece of the pattern so that all can be accounted for when the layout is complete. Glue each paper pattern piece to a piece of pearl with a very thin layer of Titebond or white glue, and let the glue dry completely. Be sure to glue edges and corners adequately, because these are likely to lift during the subsequent cutting if not glued well. I have tried rubber cement and contact glue and both have failed to hold the design in place along thin areas and at corners. These days many people design or scan inlay patterns on the computer and print them on adhesive labels and I can’t think of a single disadvantage to that approach except that you have to own a computer and printer. Otherwise, as noted use a very thin coat of Titebond or white glue (thin to avoid gumming up the saw blade), and after the glue has dried, it is time to cut the inlays. Clamp your cutting jig to a table and set up the work light. Mount a blade in the jeweler’s saw, and make certain that the teeth will cut on the downward stroke–the teeth should point toward the saw handle, which you can ascertain by running a fingertip gently along the blade in each direction. The rough, snaggy direction is opposite the one where the teeth point. Use the tensioning mechanism to tighten the blade so that it yields very little when plucked like a string (or flex the saw frame to tension the blade if you have that type of saw). When you mount the blade, be careful to avoid bending or twisting the ends, and make certain that the blade is as straight as possible. Put on your respirator or N95 and fire up the MP3 player. There are peaceful but meticulous times ahead.
To cut inlay well requires only that you be able to follow a line with the jeweler’s saw. This was easy to write, but if you are like most it will take many inlay-feet of cutting before you achieve the consistently smooth, graceful line that characterizes expert work. If you’re not already the patient sort you’ll need to learn how to be. Many artisans like to cut along the outside edge of the line, which they endeavor to keep to the left of the blade as it lays on the jig. The left hand steadies, moves, advances, indexes, and turns the pearl slab over the opening or hole in the jig and the right hand holds the saw handle beneath the jig, and saws up and down (remember, set the teeth so down is the cutting stroke) and cuts the pattern. The saw should advance, turn or otherwise move very little (except up and down)–that’s why the hole or other opening in the jig can be so small. Examine the pattern thoughtfully before you start to cut. Look for inherently weak areas, and plan the best route for the initial cut. Cut into the slab near the end of a point or corner–if you are cutting out a star, try to intersect the pattern at the apex of a point rather than somewhere along a side. When you hit a tight corner, back up the blade, cut a bit into the outside to widen the kerf, repeat if necessary, and use the widened kerf to turn the blade around the corner. When possible cut from weaker parts of the pattern into stronger sections, but learn to cut from any point in any inlay. Endeavor to cut long straight lines and curves without stopping, because a small bump or ridge often results where the cut is interrupted. Try to use the entire blade for each cutting stroke, except when you are approaching a stopping point, but even here keep you sawing movements as smooth as possible. To cut out “blind” interior sections, drill a hole into the blind pocket with a pointed bit in the Dremel high-speed drill, and then thread the saw blade through the hole and install it into the saw–this is tricky and a threaded blade is difficult to tighten, but you will improve with experience. Cut the blind sections first, and for that matter, if you have delicate sections that are not blind, try to cut them first as well. As your skill improves your pace will quicken, but be careful not to cut too fast because the blade will heat up and break. The other principal reason blades break is that they bind in tight corners or from being forced to turn too tightly to follow a tight curve. Blades also break when the metal fatigues from use, or simply because they get dull. Again, be sure you have lots of blades on hand. Blades usually just break without causing problems, but now and again a partially-cut inlay will break when the blade breaks. Likewise, once in a while a blade piece will fly when it breaks, so you might consider including goggles in your personal protective equipment arsenal. The blade can also loosen somewhat during the cutting, which actually makes it easier to cut but it wanders aimlessly. Be alert for this and tighten as necessary. If this is a chronic problem, clean the blade attachment points or buy a better jeweler’s saw frame. When the inlay is completely cut, carefully examine it for problems and then put it in the safe deposit box along with your figured pearl blanks and other irreplaceable items.
If you need to file the inlay edge(s), hold the inlay on the cutting jig and carefully file downward, slowly. A small sanding wheel in a high speed drill can be useful for some smoothing, but try to cut smooth lines with the jeweler’s saw so that you don’t have to try to improve the inlay by filing or sanding after the cutting is finished. Also, do not attempt to inlay broken pieces, glued or not. Throw them away, save them for practice with engraving, whatever, but don’t include them in a fine inlay job. If you proceed slowly, carefully, and thoughtfully your skill will improve dramatically between the time you start and finish your first elaborate pattern, so much so that you will probably want to recut some early inlays that are not as nice as later efforts. This skill will always improve, no matter how much experience you have, and you will become more critical of your own work as experience accumulates.
When you have cut all of the inlays, scrutinize them carefully. Compare and match paired patterns (such as opposite petals in the hearts and flowers pattern) so that the final product reflects care and attention to detail. Reject any inlays that are really clunky, but for a first attempt don’t be too hard on yourself. However, the really meticulous (and irreversible) work is soon to begin. Don’t use substandard inlays, for once their shapes are inscribed in wood, you’re committed to them.
Fitting or “piecing” inlays together such as in a vine or more elaborate patterns is pretty straightforward but requires experience and mega-patience to do well. First cut the inlays carefully so that minimal further work will be needed to achieve a gap-free fit. If further work is needed, use the small mill or needle file. Hold the inlay on the wooden jig or any small wooden board so that the “fitting” region barely protrudes and file carefully, horizontally, vertically, and slowly. Start at one end or corner of the design and work through it as unidirectionally as possible. Work on just one inlay in a fitted pair, not both—filing both will compound your errors (not to be confused with smoothing—you might have to do that to the joining surfaces of both inlays before attempting to file-fit them together). Try the fit frequently until the inlays fit together without gaps, in the correct orientation so that one inlay “flows” smoothly into the next as designed. If you neglect to maintain the flow between component inlays, unforeseen gaps or a cockeyed pattern will likely result when the motif is inlayed. Assemble the completed fitted motif on the table and study each joint carefully to detect gaps and places where the flow isn’t quite right, then correct the problem areas as carefully as you can to ensure that new problems don’t emerge.
Afterword:
The above applies as well to other materials commonly used for inlay. These differ physically from pearl quite substantially, but none is especially difficult to cut. Wood veneer should be glued to a paper backing before it is cut. Bone for inlay should be at least .06″ thick, because thinner bone is translucent and does not contrast well with wood. Sheet brass, nickel silver, and gold lookalikes are fairly easy to cut, although somewhat harder on jeweler’s blades than is pearl. I have no experience with stone or “reconstituted” stone composites but I expect that each has its own surmountable problems, just as pearl does. The use of ivory is rightly controversial and raw ivory is very rightly almost impossible to obtain any more. Should you wish to inlay some old ivory, old piano key tops are the most common source these days. These tend to be quite fragile and translucent and they do not make the most satisfactory inlay material. Ivory became obsolete as a decorative material in about 1862 when celluloid was invented and as a structural material it became obsolete when bone first came along (a really long time ago). In my opinion the only valid reason to use ivory is for repair of original ivory fittings or inlays on old instruments.
Continue to Part III, Routing and inlaying…
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