Tag: mother of pearl

Epiphone Sheraton II with Mother of Pearl Custom Guitar InlaysIf you’re just now join­ing us, be sure and check out part I and part II of this 3‑part series on moth­er of pearl gui­tar inlays tech­niques by Gui­tar Inlays Head­quar­ters guest writer Sean Bar­ry.

Part III–Routing and inlaying

By now you should be fin­ished cut­ting your cho­sen pearl pat­tern, and you are prob­a­bly tired of repeat­ed trips to the safe deposit box to safe­guard the prod­ucts of your efforts. Undoubt­ed­ly you have been star­ing at the high speed rotary tool and the router base that you pur­chased after you read Part I and are won­der­ing what they do. Now you shall find out.

Go one last time to your safe deposit box and retrieve your entire inlay set, and arrange it on the table in the prop­er ori­en­ta­tion. Per­haps place all of the inlays on black con­struc­tion paper so you’ll have a pre­view of your fin­ished prod­uct. With a pen­cil, num­ber each inlay, and draw a small arrow that points toward the end of the peg­head. The arrow is only nec­es­sary for radi­al­ly or bilat­er­al­ly sym­met­ri­cal inlays or for iden­ti­cal com­po­nents of such an arrange­ment with sev­er­al iden­ti­cal pieces, such as petals of a flower. Once you have scribed and begun to cut the mor­tis­es, you must avoid con­fu­sion regard­ing the pre­cise loca­tion and ori­en­ta­tion of each piece. From this point for­ward, you must not change your assigned positions–to do so will result in con­fu­sion, bro­ken inlays, and prob­lems dur­ing the final inlay­ing process. This is your last oppor­tu­ni­ty to recut any inlays that are not up the lev­el of qual­i­ty of the oth­ers, and to rearrange and rematch pieces to best advan­tage.

The next two steps are real­ly the most crit­i­cal in the entire inlay process. Up to now, if you broke an inlay or your pat­tern was uneven in qual­i­ty, the prob­lems were fixed eas­i­ly by cut­ting new pieces. After you (tem­porar­i­ly) glue your inlays in place and scribe their shapes into wood, it will be tricky at best to replace any, so take spe­cial care not to break any or to change your mind about place­ment or replace­ment.

Glue your inlays in place on the sur­face to be inlaid. In my expe­ri­ence, this is best done with DUCO cement, because this glue can be dis­solved away with ace­tone. “Spot” the glue light­ly in sev­er­al places on the bot­tom of the inlay, and press the pearl firm­ly in place on the sur­face. Check and dou­ble check the inlay posi­tion and remem­ber that it may move by itself before the glue sets up. If any do, run a few drops of ace­tone around the inlay edge, let it soak in for a few sec­onds, lift the inlay, remove the glue with more ace­tone, and try again. Script inlays (writ­ten text) are espe­cial­ly tricky and obvi­ous­ly frag­ile, and should be glued thor­ough­ly on the bot­tom. Endeav­or to clean up as much of the glue squeeze-out as pos­si­ble while it is still soft. Dou­ble-check that all inlays are prop­er­ly posi­tioned (remem­ber: gui­tars are inlaid on the 9th fret, ban­jos and man­dolins on the 10th), and set the object aside for at least 24 hours. I used to use white glue instead of DUCO, but had prob­lems remov­ing the inlays when the scrib­ing step was done. The only options are to pry up the glued inlays or to soft­en the glue with water. The for­mer can result too eas­i­ly in bro­ken inlays, and the lat­ter tends to obscure the scribe lines, so I went to DUCO (which is not per­fect but works well enough). Again, once your inlay shapes are inscribed it is essen­tial to use the same inlay that was inscribed, because it is impos­si­ble to cut anoth­er piece exact­ly like the orig­i­nal. So don’t break any by being care­less or rushed.

The next step, the most crit­i­cal­ly impor­tant in the entire process, is to inscribe the inlay out­line into the wood. Use the scribe that we dis­cussed in Part I, and trace around the inlay as close to the edge of the inlay as pos­si­ble (which should be flush with the edge). Avoid under­cut­ting the inlay, and most of all avoid push­ing on the inlay itself with the side of the scribe. At best you could dis­lodge the pearl (this only hap­pens, accord­ing to Mr. Mur­phy, to com­plex inlays and then only after the out­line is about 50% but less than 75% inscribed), and at worst you could break the inlay. This is a calami­ty if you have already inscribed any of the out­line. If your scribe encoun­ters a mound of glue, scribe care­ful­ly over it sev­er­al times until it sep­a­rates from the inlay, then scribe the wood. The wood grain will tend to divert the scribe point, so be aware of grain direc­tion changes (rel­a­tive to the inlay). Ebony is so hard that it is best inscribed by mak­ing repeat­ed pass­es. Be slow, be cau­tious, be metic­u­lous, be a per­fec­tion­ist. This is your only chance to do this step cor­rect­ly, and the qual­i­ty of your final prod­uct depends on the scribed line (and your abil­i­ty to fol­low it with the high speed drill). I have tried to deep­en the scribed lines lat­er, after the inlay is removed, but with very lim­it­ed suc­cess. Even though the pearl is not sup­posed to be a “fence,” its pres­ence offers a much bet­ter visu­al lim­it than does the scribed line alone. Inspect each scribed line care­ful­ly and make cer­tain that all are com­plete and deeply inscribed.

With a glass eye­drop­per, drib­ble some ace­tone care­ful­ly around each inlay, but just do one or two at a time. Be extreme­ly care­ful not to allow ace­tone to con­tact fin­ish or plas­tic bind­ings, as it will cor­rode them. Also, heed the fire haz­ard. After the ace­tone has con­tact­ed the inlay for a few min­utes, gen­tle side pres­sure will usu­al­ly dis­lodge it. Allow very del­i­cate inlays to soak up the ace­tone for at least 30 min­utes, and then use the gen­tlest side pres­sure dis­trib­uted over the entire inlay to dis­lodge it. Be very careful–it will be almost the ulti­mate in dis­heart­en­ing feel­ings to break the inlay now, exceed­ed only by break­ing it lat­er. After each inlay is dis­lodged, take a moment to clean the resid­ual glue from the inlay bot­tom and crevices, and renew the label and arrow (the ace­tone may tend to dis­perse the pen­cil marks, and it will dis­solve away vir­tu­al­ly any ink). Arrange the pieces care­ful­ly because you don’t want to make any fit­ting mis­takes dur­ing the rout­ing process attrib­ut­able to try­ing to fit the wrong piece or ori­ent­ing an inlay incor­rect­ly.

Fre­quent vari­a­tion: Some arti­sans trans­fer inlay shapes to the wood sur­face by coat­ing the wood with a spray adhe­sive such as 3M, hold­ing the inlay in place by press­ing on it with a tooth­pick or some oth­er slen­der imple­ment, and coat­ing the entire wood sur­face with blown or shak­en fine white pow­der such as tal­cum or corn starch. No scrib­ing is involved, and the inlay shape stands out on the dark wood in stark con­trast to the white pow­der which is bound to the adhe­sive. This method is eas­i­er and less involved than scrib­ing and its adher­ents main­tain that it makes the inlay shape more dis­tinct and eas­i­er to fol­low than scribed lines. Draw­backs are that the pow­der may not cov­er even­ly which you won’t know until the inlay is lift­ed, and that when you start your mor­tise work you may have prob­lems see­ing the bound­ary between black and white clear­ly, espe­cial­ly if you inad­ver­tent­ly cross into the “no cut” zone. Anoth­er con­cern is that you are poten­tial­ly aerosoliz­ing fine pow­ders that have unknown poten­tial when inhaled so if you use this tech­nique remem­ber your res­pi­ra­to­ry pro­tec­tion. Talcum’s pur­port­ed haz­ards are con­tro­ver­sial and uncon­firmed but the mate­r­i­al is like­ly pret­ty innocu­ous if not inhaled. Some peo­ple are sen­si­tive to tal­cum so if you start itch­ing when you try this tech­nique you should prob­a­bly aban­don it.

Now comes the three-step rout­ing process, the most dif­fi­cult part of inlay tech­nique. You must wear gog­gles and a res­pi­ra­tor or N95 mask, you must keep a steady hand, you must STOP if you can’t see clear­ly where you are cut­ting, you must cut very slow­ly, and you must keep the faith in your scribed lines, even though many times they don’t seem to be cor­rect. The first step is to cut the inlay out­line deeply with the point­ed den­tal bit (again, the point­ed bits offered by Dremel tend to be too large, but they will work for many larg­er inlays as long as there aren’t tight cor­ners). Use the drill free­hand, not in the router base, and cut down­ward and side­ways with the point of the bit from the line into the wood. Hold the drill like a pen­cil and use the low­est speed, but vary this to suit the hard­ness of the wood and the part of the out­line you are cut­ting. This is actu­al­ly the most dif­fi­cult of the three steps, and it must be done slow­ly. BE SURE TO CUT INSIDE THE LINE!! Only expe­ri­ence will help you improve, but this step will estab­lish how “close” your inlays are, that is, how much filler space results. Try to cut 2–3 mil­lime­ters down into the wood. If you can’t see your scribed line clear­ly, stop and rearrange the work­piece until you can. For­mer­ly, I used two or three 25-pound bags of #7 lead shot (avail­able from shot­gun reload­ing sup­pli­ers) to pad and sup­port a typ­i­cal fin­ished neck but I sus­pect that too much lead dust emanat­ed from those bags so I now use sand bags instead. These give great flex­i­bil­i­ty on repo­si­tion­ing and do not dent or nick the wood. For unshaped necks as described ear­li­er padding is less impor­tant but the bags still help for posi­tion­ing. Cut com­plete­ly around the inside of each scribed line, and exam­ine each very crit­i­cal­ly to make sure the ini­tial mor­tise is of uni­form depth and that the cor­ners and tight curves are cut ver­ti­cal­ly and clean­ly. When you are sat­is­fied that all is well, exam­ine the work­piece once again. I have nev­er failed to find spots that need­ed work, even after two or three exam­i­na­tions.

Next, chuck the router bit or minia­ture end mill (not the ball-end bit) into the high speed drill, and mount the drill in the router base. Leave enough bit exposed so that it will cut a mor­tise to about 95% of the thick­ness of your inlays. To check, use scrap wood and adjust the bit depth so that one of your inlays pro­trudes just slight­ly above the mor­tise. If you are inlay­ing large pieces in a curved sur­face (D‑45 hexa­gons in a gui­tar, for exam­ple), your mor­tis­es will be curved as well unless you shim the bot­tom of the router base with tape and wood veneer so that it rides per­pen­dic­u­lar to the peak of the fin­ger­board. For these inlays, set the cut­ting depth to 95–98% of the pearl thick­ness. If you are inlay­ing a lam­i­nate such as Abal­am, you must cut your mor­tis­es so that the inlay is flush or very near­ly so—the out­er lam­i­nate is very thin and easy to sand through dur­ing the lev­el­ing process (described lat­er). Lam­i­nates obvi­ous­ly won’t usu­al­ly work across curved sur­faces. Straight router bits func­tion best at very high speed, so use the high­est speed set­ting. Use the router bit to remove as much of the inlay mor­tise wood as pos­si­ble, but do not encroach the edge too close­ly because if you slip this bit will cut real­ly fast and do ter­ri­ble, irrepara­ble dam­age. For that rea­son do not try to take large “bites” of the wood in the mid­dle of the mor­tise either. Work slow­ly and method­i­cal­ly, and be care­ful. If you can’t see very clear­ly, STOP and rearrange the work­piece so that you can. Cut out all of the mor­tis­es and then exam­ine them crit­i­cal­ly. Do not yet attempt to fit the inlays, because the mor­tis­es are not quite ready, and you may break an inlay if it binds in a mor­tise.

Now chuck the tiny ball-end bit into the drill (leave it in the router base) and set the bit depth so that the ball cuts flush with the bot­tom of the rout­ed mor­tise, not into it because you don’t want to deep­en the mor­tise any­where. How­ev­er, if with this set­up the top of the ball is flush or with­in 1mm of the wood sur­face, the bit must be set deep­er because oth­er­wise it will great­ly enlarge your mor­tis­es along the edges. You are going to under­cut the edges of the mor­tis­es, and if the ball is too close to or at the sur­face it will over­cut them too. The ball diam­e­ter of this bit should slight­ly exceed the shank diam­e­ter, and should nev­er be small­er than the shank–the shank rubs against the wood “fence” (the edge that you estab­lished with the point­ed bit) and thus keeps the ball from under­cut­ting too deeply, but it must under­cut a lit­tle or the inlay may bind when it is insert­ed. Use low or medi­um-low speed and go around the edges of your mor­tis­es very slow­ly and care­ful­ly with the ball. Be very aware of the pre­vi­ous­ly estab­lished mor­tise lim­its, and do not exert any pres­sure against the wall of the mor­tise with the bit shank. Oth­er­wise the spin­ning shank will tend to erode the wood and enlarge the mor­tise, and unfor­tu­nate­ly you will be unable to see this because your scribed lines are now obscured. Tight cor­ners and nar­row curves may not admit the bit shank, and so these will be unreach­able with the ball. Use the point­ed bit free­hand again to under­cut these. When this job is com­plete inspect each mor­tise care­ful­ly and recut any ques­tion­able spots. It is not unusu­al to spend hours with each large mor­tise (and some­times with small ones as well). Be pre­pared to devote lots of time to a large inlay project.

Now remove the drill from the router base and chuck the point­ed bit again, and begin fit­ting the pearl inlays in their mor­tis­es. Once again exam­ine each mor­tise for any rough edges or uneven lines, and smooth them care­ful­ly with the point­ed bit. Gen­tly press the inlay into place. If it won’t go in eas­i­ly, stop and find out why. Some inlays go a short dis­tance and bind, and then yield to slight­ly greater pres­sure and slip in to full depth. This is undesirable–remove the inlay, find out where it is bind­ing, and smooth the edge. If you don’t, even slight expan­sion of the wood dur­ing sea­son­al changes may crack the inlay. Tight spots are usu­al­ly vis­i­ble after the inlay is removed because the pearl leaves a white mark. Exam­ine such spots care­ful­ly and decide how deeply to cut into the wall of the mor­tise. This is where all of your care­ful ear­ly work can be com­pro­mised by impa­tience, so use good judg­ment about enlarg­ing the mor­tise. If you stayed with­in the scribed line any bind­ing has to be the result of lit­tle ridges and bumps on the mor­tise edge between the top of the ball-cut and the top sur­face of the wood. Look care­ful­ly for these and smooth them a lit­tle, then try to fit the inlay again. I have mod­i­fied a dis­card­ed den­tal “ele­va­tor” into a tiny chis­el for clean­ing out areas that will not admit even the tini­est of den­tal bits. I don’t need it very often, but when I do noth­ing else seems to work. It is rel­a­tive­ly rare for any inlay to fit per­fect­ly on the first try, but it will become more com­mon as your skill and expe­ri­ence accu­mu­lates. Now and again a del­i­cate inlay (espe­cial­ly script) will become wedged in the mor­tise so that it is very dif­fi­cult to remove. You must resist the temp­ta­tion to 1) pry it out oth­er than extreme­ly gen­tly; 2) leave it in place and attempt to pack filler around it. Work very care­ful­ly with tooth­picks around the edges, and lift it out. It will come, but if you don’t work care­ful­ly it will break. Then find out where it is bind­ing and smooth the edge.

Once all of the inlays are fit­ted they can be glued into place, and any gaps between the pearl and the mor­tise edge filled at the same time. The process is sim­ple: fill the mor­tise with a glue/filler, press the inlay into place, lev­el it, allow the filler to set up, and file, scrape, and sand the inlay flush. The stan­dard glue/filler has been epoxy with dust from the same type of wood mixed in for col­or and tex­ture. This works well with ebony, but far less so with rosewood–finely-divided rose­wood dust mixed with epoxy is usu­al­ly much dark­er and green­er than sol­id rose­wood. Some arti­sans use tint­ing col­ors, such as are used to tint house paint, with some suc­cess for rose­wood, but I have yet to see a per­fect match for rose­wood with any col­or­ing sys­tem. I just use rose­wood dust and try to keep the mor­tis­es as close as pos­si­ble.

Not all epox­ies work well as inlay filler. My pearl inlay men­tor exper­i­ment­ed dur­ing the 1960’s with var­i­ous epoxy brands to find those that set up hard (with­out a tacky sur­face) and that crept min­i­mal­ly. Epox­ies are tech­ni­cal­ly flu­ids even when set, and tend to flow just like water, except much slow­er. Real­ly creepy epox­ies soon leave gaps and pits in the fill space, and a supe­ri­or inlay job can end up look­ing very infe­ri­or. My men­tor select­ed Wil­hold epoxy, and I fol­lowed his advice with good results for years. Wil­hold epoxy is no longer with us and I now use Epoxy 220, a long-cure two part prepa­ra­tion avail­able from jew­el­ers sup­pli­ers and oth­er sources and I’m about as sat­is­fied with its per­for­mance as I was with Wilhold’s. I know that many are using five-minute epoxy, and I guess this is all right except that one must mix sev­er­al batch­es in the course of an inlay job, and many of these prepa­ra­tions nev­er lose a slight tack. I think the best choice is the light-col­ored long-set/­long cure mate­r­i­al, and the appro­pri­ate goal is to devel­op your skills enough so that you need very lit­tle or no filler at all. What­ev­er epoxy you use, be sure to mix dead-equal quan­ti­ties of resin and cat­a­lyst, because a mix­ture of unequal quan­ti­ties, par­tic­u­lar­ly an excess of resin, tends to creep for­ev­er. I make up the mix­ture, stir care­ful­ly to ensure uni­for­mi­ty, and mix with just enough wood dust to yield a flu­id mix­ture of the cor­rect col­or. In my expe­ri­ence, the best dust is pro­duced by fil­ing wood with a met­al file, as oth­er dust may be too coarse or may be mixed with “impu­ri­ties” (sand­pa­per abra­sives, etc). Some arti­sans insert the inlay, pack wood dust into the crevices, and then sat­u­rate the dust with cyano­acry­late glue which sets up in sec­onds. The work I’ve seen that used this method looked good, but time will tell whether the glue remains sta­ble enough to keep the inlays in place down through the decades. I have my doubts.

If you are using long-set epoxy, you can fill all of the inlay mor­tis­es to about 3/4 depth with the epoxy filler. If you are using five-minute mate­r­i­al, only fill one or two large mor­tis­es at a time. I empha­size this–if your epoxy sets up before you embed the inlay, you will have to re-rout the mor­tise. After the req­ui­site num­ber of mor­tis­es is filled, press each inlay into place, and lev­el it by rock­ing gen­tly with a cou­ple of tooth­picks or thin dow­els. Anoth­er advan­tage of long-set epoxy is that there is time to self-lev­el pri­or to embed­ding the inlay. Be very care­ful not to let epoxy flow into the fret slots! Embed all of the inlays and dou­ble-check each to make cer­tain that they are seat­ed to full depth and that the filler has oozed out all around. Make sure that no inlay is tilt­ed. In the past I have applied heat from a high-inten­si­ty read­ing lamp to each inlay-filler to increase flu­id­i­ty and allow bub­bles to escape, but this prac­tice is now dis­cour­aged because it has been shown that most epox­ies lib­er­ate tox­ic gas­es such as phos­gene when heat­ed. This prac­tice also accel­er­ates the cure, so that long-set epoxy when heat­ed may hard­en in just a few min­utes. In any case, allow the epoxy to hard­en com­plete­ly before pro­ceed­ing.

The final steps are to clean up the excess filler and lev­el the inlays with the sur­round­ing wood. I use a cab­i­net scraper, a dou­ble-cut mill file, and a hard rub­ber sand­ing block with var­i­ous grits from 80 (pret­ty coarse) through 600 (pret­ty fine). Start with the (dull) scraper and shave away the epoxy from around and on top of the inlay. Be very care­ful in this and the fol­low­ing steps not to gouge or oth­er­wise dam­age the sur­round­ing wood. Con­tin­ue to shave until most of the epoxy is gone. A coarse mill file can take the process a step fur­ther and begin to lev­el the inlays with the wood, but again please be care­ful not to dig into the wood. Final­ly, use the sand­ing block alter­nate­ly with the scraper on each inlay (avoid the sur­round­ing wood, because it is much soft­er than the inlay and will erode at a much high­er rate–this will result in high and low spots). Change to 120 grit after the inlays are com­plete­ly lev­eled and flush with the wood, and sand care­ful­ly to remove the 80-grit scratch­es. I emphasize–use a sand­ing block, or at least use sand­pa­per fold­ed over a thick piece of cork. Do not use your fin­gers as a sand­ing pad for this or any oth­er oper­a­tion in lutherie. If large bub­ble holes show up in the filler, take an extra day to fill them and to cure the new epoxy, then lev­el with the sand­ing block and scraper. After the 80-grit scratch­es are gone, move on in turn through 220, 320, 400, and 600 grits (all used dry). Sand the entire fin­ger­board with all of the grits from 220 and fin­er. By the time you get to 600, the inlays should be free of vis­i­ble scratch­es and they should look pret­ty good against the dark wood. You should be beam­ing with pride.…

Care­ful­ly clean out the fret slots with an X‑Acto knife and #11 blades, and with a vac­u­um clean­er hose before you attempt to install frets.

I don’t oil fin­ger­boards, oth­er than to allow skin oils to put the char­ac­ter­is­tic pati­na in the board with time and play­ing. I have found that a final vig­or­ous pol­ish with a cloth dia­per or dish tow­el does at least as nice a job as oil on the board and inlays, and does­n’t add any chem­i­cals to the wood, so I rec­om­mend that approach over any oil, plant-derived or not. Oils also soft­en fin­ger­board wood, may cause fin­ish to peel away from the wood along the edges of the fin­ger­board, may loosen frets and inlays, and do not actu­al­ly pre­vent mois­ture move­ment across fin­ger­boards (prop­er sea­son­ing does that). Avoid them—they’re up to no good.

Engrav­ing: If your pat­tern involves engrav­ing, now is the time. Engrav­ing is an advanced tech­nique that requires much prac­tice and study to mas­ter, and the tech­nique itself when done well has sub­tle­ty that defies sim­ple instruc­tion. The basics of engrav­ing are sim­ple enough–purchase some gravers, draw some lines on the inlays, etch, deep­en, and widen the lines as appro­pri­ate with the graver(s), and use Laskin’s black filler, the epoxy-ebony dust mix­ture, or per­haps col­ored inks to dark­en and col­or the engraved lines. If you’re just copy­ing an estab­lished pat­tern all you real­ly need is practice—glue some scrap pieces of pearl to a piece of wood and prac­tice your engrav­ing on them until you have the con­fi­dence you need to do a cred­itable engrav­ing job.

To become a mas­ter engraver you need to devel­op your graph­ics skills as much as your engrav­ing tech­nique. If you want to inlay a “real” object (human, ani­mal, etc) to be engraved, start with pho­tographs and detailed sketch­es of the object, and a sketch of the inlay. Use the pho­tographs and oth­er visu­al aids lib­er­al­ly to help you envi­sion the accents need­ed to lend dimen­sion and real­ism (assum­ing that’s the artis­tic goal). Pen­cil the lines on the sketch, ver­i­fy that each line is need­ed, and then when the inlay is com­plet­ed exe­cute each line on the inlay with style and con­fi­dence. Strive to achieve smooth curves, cor­rect­ly tapered and deep­ened cuts, appro­pri­ate accents and shad­ing, anatom­i­cal accu­ra­cy, good per­spec­tive, and dimen­sion­al res­o­lu­tion, all of which char­ac­ter­ize expert engrav­ing. As with every­thing else that we have dis­cussed, start sim­ple, build method­i­cal­ly from there, and don’t rush. Inex­pert engrav­ing can detract from oth­er­wise good inlay, so be sure of your skills before you com­mit to an inlay job that requires engrav­ing. Hint: try to devote some time watch­ing an expert inlay engraver at work.

Dot inlays: Pur­chase the cor­rect dots, pur­chase a match­ing brad-point drill bit, pur­chase a drill press. Do not attempt this with a hand drill. Drill the holes to near­ly full depth, press each dot into place, put a drop of cyano­acry­late glue (Crazy-Glue or sim­i­lar) around the edge of the inlay, let it set up, sand off the glue and pro­trud­ing pearl and pol­ish as above. I’m not so con­cerned about the longevi­ty of cyano­acry­late for this appli­ca­tion because the dots usu­al­ly fit tight­ly and the glue may just cre­ate a vac­u­um under the inlay so the dots won’t move even if not tech­ni­cal­ly “stuck” in place. Some of the old Gib­son Mas­ter­tone pat­terns use small dots in flo­ral array—purchase the appro­pri­ate size dots, don’t try to cut them with the jew­el­er’s saw because such hand-cut dots will usu­al­ly make an oth­er­wise glo­ri­ous inlay job look clunky.

Resources: There are web­sites galore devot­ed to inlay—take time to vis­it as many as you can. Most steel string gui­tar con­struc­tion books include sec­tions on inlay tech­nique, as do Roger Siminoff’s books on man­dolin and ban­jo con­struc­tion. All of these ref­er­ences have much to offer and some have rather dif­fer­ent approach­es than what I have described. An old­er but very use­ful print ref­er­ence on inlay tech­nique is James Patterson’s “Pearl Inlay,” (revised in 1988) which cov­ers lots of ter­ri­to­ry includ­ing how to pro­duce your own blanks and strips from raw shell. A some­what new­er ref­er­ence also now in its sec­ond edi­tion is Lar­ry Robinson’s “The Art of Inlay,” which includes instruc­tions on the inlay process and has many great pho­tographs of Larry’s phe­nom­e­nal pieced inlay work. Lar­ry “works large” and has devel­oped an elab­o­rate tech­nique for filler-free inlaid motifs with mul­ti­tudes of amaz­ing­ly well-fit­ted com­po­nent pieces. His work is stun­ning, his book is superb, and you should be able to get lots of ideas on using var­i­ous inlay mate­ri­als to best advan­tage. Lar­ry has also pro­duced a series of DVDs on inlay which I haven’t seen but I can’t imag­ine would be any­thing less than great. My oth­er favorite book on inlay is William “Grit” Laskin’s “A Guitarmaker’s Can­vas.” Grit also does phe­nom­e­nal pieced work with numer­ous inlay mate­ri­als, and like Lar­ry he is a mas­ter engraver. I nev­er tire of gaz­ing at Grit’s aston­ish­ing and evoca­tive inlaid scenes and it is tempt­ing to think that he and Lar­ry have tak­en instru­ment inlay as far as it can be tak­en. But Grit, Lar­ry, Renee Karnes, and oth­ers are proof that at about the time we think we’ve seen the apex, along comes some­one whose design tal­ents and inlay tech­nique sur­pass that apex by a mile. New hands will bring fur­ther accom­plish­ments, more inspi­ra­tion, new pin­na­cles. Prac­tice, think, use your imag­i­na­tion, con­tin­u­ous­ly improve your draw­ing, lay­out, and inlay­ing skills, think some more, devote the learn­ing time, prac­tice some more, and try to make your hands the new hands.

Sean Bar­ry
Davis, Cal­i­for­nia
Octo­ber 2011

Epiphone Sheraton II with Mother of Pearl Custom Guitar InlaysII. 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…

Epiphone Sheraton II with Mother of Pearl Custom Guitar InlaysThis arti­cle is a 3‑part mon­ster from my friend Sean Bar­ry down in Davis, CA. It is bar-none the best arti­cle on pearl inlay on the Inter­net, in my hum­ble opin­ion. When I was writ­ing my own MOP arti­cle for Gui­tar Inlays Head­quar­ters and research­ing the sub­ject, I found Sean’s old arti­cle and asked him if I could reprint it here. Being the nice guy he is, he not only said we could print it here, but he also revised it with updat­ed infor­ma­tion for 2011. I bring you Moth­er of Pearl Inlay Tech­nique, part I, part II, and part III.

Take it away, Sean…

Mother of Pearl Inlay Technique, Part I

This is a three-part dis­cus­sion about the prac­tice of stringed instru­ment inlay. Part I cov­ers the prin­ci­pal mate­ri­als and tools, Part II cov­ers pearl cut­ting and lay­out tech­niques, and Part III cov­ers inlay­ing tech­nique. The usu­al dis­claimers apply–I rec­om­mend spe­cif­ic brands only when either no oth­er will work or I have no expe­ri­ence with oth­ers. As far as I know, no man­u­fac­tur­ers men­tioned here have ever heard of me. Your feed­back is solicit­ed and wel­come. Feel free to down­load the text for per­son­al use, but oth­er­wise please do not cross­post, for­ward, or repro­duce the text with­out per­mis­sion.

2011 revision:

I wrote “Pearl Inlay Tech­nique” in three parts over about two months in late 1995. I post­ed the parts one by one in plain text and ASCII art in the old USENET news­group sys­tem (rec.music.makers.builders and alt.banjo), and the series made its way all around the then fledg­ling “World Wide Web.” The response from estab­lished and aspir­ing luthiers and inlay arti­sans was unex­pect­ed, grat­i­fy­ing, and to my amaze­ment pret­ty con­stant over these 16 years—folks still find the series through some dusty link or anoth­er and appar­ent­ly the arti­cles still res­onate with those who want to learn how to inlay moth­er of pearl. But much has changed since 1995 in the world of inlay and in my world too, not to men­tion in the way we dis­sem­i­nate infor­ma­tion online. Par­tic­u­lar­ly because of the lat­ter I’m some­what ret­i­cent to revise and redis­trib­ute the arti­cles, and yet some of the infor­ma­tion is suf­fi­cient­ly dat­ed to make me think I should either revise the trea­tise or search it out and pull it down wher­ev­er I find it. Since the lat­ter is impos­si­ble and since I still have some cre­ative streaks remain­ing in my aging frame, I decid­ed to revise the text and float it out there once again.

Acknowledgements:

I want to thank all who took the time to write to me about the first edi­tion of “Pearl Inlay Tech­nique,” and I also want to thank sev­er­al indi­vid­u­als who start­ed me down this path so many years ago, either through direct instruc­tion and con­ver­sa­tion, or through their first-rate writ­ing. Thanks to Don­ald Zepp, Roger Simi­noff, Frank Ford, Richard John­son, Hideo Kami­mo­to, Ervin Som­o­gyi, Don Muss­er, Mike Long­worth, and most of all to my good friend Chuck Erik­son, the incom­pa­ra­ble Duke of Pearl.

The text that fol­lows describes one person’s method for inlay­ing moth­er of pearl and sim­i­lar mate­ri­als into wood. There are as many vari­a­tions on each step and indeed on the entire process as there are peo­ple who inlay pearl, so if you run across instruc­tions that devi­ate from the para­graphs below (or vice ver­sa), please adopt or stay with what works best for you. Prac­tice first, so you know which way that is.

I. Materials and tools

Any num­ber of flat or flat­ten­able mate­ri­als can be inlaid into the sur­faces of instru­ments, fur­ni­ture, jew­el­ry box­es, etc., but the most pop­u­lar for stringed instru­ments has always been moth­er of pearl from pearl oys­ters and a sim­i­lar­ly-derived mate­r­i­al from abalone shells. Moth­er of pearl (nacre) is the inte­ri­or lin­ing of the pearl oys­ter (Pinc­ta­da species) shell, and although all shelled mol­lusks pos­sess a shell lin­ing that resem­bles moth­er of pearl, the pearl oys­ter and abalone shell lin­ings are par­tic­u­lar­ly appeal­ing and the shells are large enough to yield rea­son­ably large flat pearl blanks. Oys­ter moth­er of pearl is usu­al­ly white, gold, or gray­ish pur­ple (“black”) with red, blue, and green iri­des­cence and often with swirl, “eyes,” a curly pat­tern like “fid­dle­back” maple, or oth­er fig­ure that results from prox­im­i­ty to the shell hinge or from imper­fec­tions or worm bor­ings in the out­er shell.

Pearl oys­ters are native to the warmer parts of the Pacif­ic and Indi­an Oceans, from the Gulf of Cal­i­for­nia to the Red Sea, and they are “farmed” in Asia for the cul­tured pearl indus­try. I don’t know if they are also used for food. I also don’t know what, if any, per­cent­age of the pearl oys­ter shells that are import­ed for inlay pearl orig­i­nate in cul­tured oys­ter beds, but I hope it’s large. Abalone (sev­er­al Hali­o­tis species, of which Cal­i­for­nia red and green abalone are the most pop­u­lar for inlay) occurs pri­mar­i­ly in mod­er­ate­ly cold water parts of the Pacif­ic Ocean. Cal­i­for­nia abalone for inlay orig­i­nates entire­ly from “wild” spec­i­mens har­vest­ed for their meat, which is con­sid­ered an ulti­mate seafood del­i­ca­cy. Some abalone is now farmed, and per­haps in the future most of the com­mer­cial mate­r­i­al for food and shell can orig­i­nate from such sources. Abalone lam­i­nates (“Abal­am”) are now wide­ly avail­able and are par­tic­u­lar­ly use­ful for pur­fling appli­ca­tions and for large inlays in flat sur­faces. (2011 note: West coast and Mex­i­can red abalone, for­mer­ly the inlay mar­ket sta­ple, is now scarce and expen­sive and it has been large­ly replaced by west­ern Pacif­ic “paua” abalone and to a less­er extent by green abalone, both of which are also expen­sive).

Oth­er mate­ri­als occa­sion­al­ly or com­mon­ly used for instru­ment inlay, at least his­tor­i­cal­ly, include bone, ivory, tor­toise shell, sil­ver, gold and its imi­ta­tors, brass, nick­el sil­ver, stone and stone com­pos­ites, and var­i­ous woods and plas­tics (“moth­er of toi­let seat”). Each has its own pecu­liar­i­ties, but the process for cut­ting and inlay­ing all such mate­ri­als is basi­cal­ly the same.

To con­vert an arched shell to flat inlay blanks requires sev­er­al steps. The first is to mark the shell (on the inside) to take best advan­tage of the fig­ure and pat­tern, and to min­i­mize the arch in any par­tic­u­lar rough piece (the less arch, the larg­er and thick­er the final blank). The result­ing jig­saw puz­zle in the shell is then band­sawn into arched indi­vid­ual pieces that are lined with moth­er of pearl on one side and with the shell exte­ri­or on the oth­er. The rough exte­ri­or sur­face is then ground away to reveal the under­ly­ing moth­er of pearl. The result­ing piece is any­where from <1mm to 25mm thick (up to 1″ (25.4 mm) for real­ly thick shells at the lip), and it is still arched. Next the arched blank is fed into a spe­cial grinder that flat­tens and fin­ish­es each face of the blank, accom­pa­nied by pro­duc­tion of much dust. The fin­ished blanks are char­ac­ter­is­ti­cal­ly no more than 0.06” thick. Many sup­pli­ers fur­nish two thicknesses—thin (about 0.04”) for inlay­ing flat sur­faces, and thick (about 0.05–0.06”) for arched fin­ger­boards. The amount of hand­work that goes into plan­ning, mark­ing, band­saw­ing, and pre­lim­i­nary grind­ing ren­ders the blanks rather expen­sive. Blanks may be sold by the piece or by weight–thin blanks when sold by weight are usu­al­ly more expen­sive because there are more blanks per unit weight and there­fore more labor is involved in pro­duc­ing that unit weight.

The tools nec­es­sary for cut­ting and inlay­ing pearl include good light­ing, a jew­el­er’s saw, a home­made cut­ting jig, a scribe with a sharp met­al point that is hard and stiff enough to scribe very hard wood, a few nee­dle and small mill files, a hand held high speed drill (aka high speed rotary tool) with a router attach­ment, var­i­ous bits and appro­pri­ate col­lets for the drill, a jig or vise to hold the object to be inlayed, and a 2.5″ x 5″ or sim­i­lar rub­ber sand­ing block. For light­ing, use a swing-arm lamp to give best con­trol of angle and inten­si­ty. The jew­el­er’s saw resem­bles a cop­ing saw with a very slen­der blade, and the saw and the blades are avail­able from luthi­er, jew­el­ers, and lap­idary sup­pli­ers. Blades are typ­i­cal­ly retailed as “fine,” “medi­um,” and “coarse,” but the actu­al thick­ness­es vary among retail­ers because dozens of thick­ness­es are avail­able from the man­u­fac­tur­ers. I use “medi­um” blades for most of my work because they are less sub­ject to break­age than fine blades and less like­ly to bind and break the inlay sheet than coarse blades. Fine blades are usu­al­ly rec­om­mend­ed for scroll­work and oth­er intri­cate inlays, but as your skill increas­es you will have less need for them. Begin­ners should pur­chase at least 2–3 dozen blades. Many inlay arti­sans use a jew­el­er’s saw with an adjustable throat to accom­mo­date vari­a­tions in sup­plied blade length. Such an adjust­ment fea­ture also per­mits the use of bro­ken blades, but in my expe­ri­ence this is a waste of time unless the blade was bro­ken before it was ever used. The home­made cut­ting jig is a piece of hard­wood such as maple, birch, or oak about 12″ long x 2–3″ wide x 3/4″ thick. Two com­mon shapes of the busi­ness end of the jig include a slot with a small hole a few inch­es from the end of the jig, or a tri­an­gu­lar cutout:

Triangular Cutout Jig for Cutting Custom Guitar Inlays

The jig is clamped flat to a table so that the slot and hole or V‑notch extends beyond the edge, the pearl sheet is posi­tioned over the open­ing, and the wood sup­ports the sheet while the saw cuts down­ward. The scribe is used to inscribe the exact shape of the inlay into the wood that will be rout­ed for the inlay. Many hard­ware stores sell util­i­ty scribes–the one I use is a knurled steel shaft with a fair­ly fine hard­ened steel point that is remov­able with pli­ers. Spare points are stored at the oppo­site end of the scribe, which is sealed with a hexag­o­nal plas­tic cap. A small mill or nee­dle file may be handy for remov­ing the small spur that some­times remains at the end of the blade path and for fit­ting indi­vid­ual inlays togeth­er in larg­er motifs such as the “vine of life.”

The high speed drill is used to delin­eate and rout the inlay mor­tis­es in the wood. The most com­mon­ly used drill for inlay work is prob­a­bly the Dremel Moto-Tool, which has been in pro­duc­tion in one ver­sion or anoth­er since the 1930s and has a well-deserved rep­u­ta­tion as one of the most use­ful of luthier’s tools. Be sure to check out oth­er high speed drill options such as the Prox­xon or the Black and Deck­er, but do not econ­o­mize on the high speed drill: pur­chase a vari­able speed, ball-bear­ing mod­el, and if you can afford it, pur­chase two. Three is not too many. You’ll also need a router attach­ment for the high speed drill. The choic­es for this impor­tant attach­ment have changed quite a bit in the past 16 years. I believe that most cur­rent Dremels work with the cur­rent Dremel “plunge router attach­ment,” but the base on that device is huge, much too large for inlay work in tight cor­ners. Anoth­er option is the Stew­art Mac­don­ald “pre­ci­sion router base” (stan­dard dis­claimers), which is thread­ed to fit many post-1995 Dremels. It is a com­pact well-designed, rea­son­ably pre­ci­sion acces­so­ry that is also a bit tricky to learn to adjust and use effec­tive­ly. Research the alter­na­tives, decide which you like bet­ter, and make sure that your cho­sen drill is com­pat­i­ble with your cho­sen base before you pur­chase. I have a cou­ple of old-style Dremel router bases that fit the clas­sic, dis­con­tin­ued Dremel 380, and I con­fess that I use that old but use­ful com­bi­na­tion for the stages of my inlay work that require the router base. Ebay, as though you were won­der­ing. I mod­i­fied the router base by replac­ing the bot­tom plate with piece of 1/8”plastic 17/8” front to back and the same width as the orig­i­nal base so that the bit is not sur­round­ed by plas­tic and I can see the oper­a­tion clear­ly. With this mod­i­fied router base I can also access just about any tight cor­ner with the bit. The nar­row base set­up is prone to tip­ping but the trade­off in access and vis­i­bil­i­ty is worth that minor incon­ve­nience.

Numer­ous bits, sanders, cut­ting wheels, buffers, etc. are avail­able for high speed drills, but I have found that just three bits are nec­es­sary for inlay. These include a fine-point­ed bit, a bit with a plain shaft that ends in a tiny cut­ting ball that is slight­ly larg­er in diam­e­ter than the shaft, and a cou­ple of fair­ly large (1/16″ and 1/8” are good sizes) router or down­cut bits. The point­ed bit is used in the tool free­hand to delin­eate and cut down the edge of the inlay mor­tise, the router bit is used in the router base to hog out waste wood in the mid­dle of the mor­tise and to even up the mor­tise depth, and the ball-end bit is used on the tool also in a router base to under­cut the edge after the mor­tise is most­ly com­plet­ed. Because most “hob­by­ist” point­ed and ball-end bits are gen­er­al­ly too large for small inlay work, I use den­tal bits that I obtained for free from my dentist–used bits are entire­ly sharp enough for inlay, and will remain sharp for a long time. Quite a vari­ety of den­tal bits is avail­able, from excep­tion­al­ly fine­ly-point­ed car­bide bits to tiny ball- and cone-shaped car­bides and var­i­ous straight and point­ed dia­mond bits. One request to my den­tist and a 30-day wait yield­ed a life­time sup­ply, even if I live a real­ly long time. Since the bits were at one time exposed to human cells and tis­sues ask your den­tist to steam-ster­il­ize the bits in an auto­clave. If for some rea­son this is not pos­si­ble, you could ster­il­ize them your­self in a pres­sure cook­er. Don’t immerse the bits in water in the cooker–sterilization comes from pro­longed con­tact with pres­sur­ized steam, which can’t hap­pen if the bits are immersed in water. Instead, place them in a clean tuna can with some mar­bles for bal­last, and place the can in about one inch of water in the cook­er. Process for at least 30 min­utes on high heat after the cook­er seals (the auto­clave stan­dard for ster­il­iza­tion is 30 min­utes at 250ºF (121ºC) and 15 psi).

You will still need the router bits, and you will need one or more col­lets for your drill sys­tem to match the den­tal bit shanks which are small­er than most stan­dard Dremel bit shanks (1/8”). Very hard (ebony) or very hard and resinous (rose­wood) woods are noto­ri­ous­ly hard on router bits unless the bits are made of durable mate­ri­als like tung­sten car­bide. Most hob­by­ist 1/8” shank router bits are not car­bide, and the car­bide coat­ed gen­er­al cut­ting bits that Dremel offers are too large for small inlay rout­ing and they do not cut hard woods very well. For rout­ing work I use car­bide spi­ral down­cut bits (aka minia­ture end mills) with 1/8″ shanks that fit the stan­dard 1/8” col­let, avail­able from var­i­ous lutherie and machine tool sup­pli­ers such as MSC. These cut ebony rea­son­ably well, are avail­able in sizes that range from tiny (1/64”) to sub­stan­tial (1/8”) and except in the small­est sizes they are not expen­sive which is good because they will prob­a­bly burn after a cou­ple of hours of use on ebony and prob­a­bly soon­er on rose­wood. If you find minia­ture straight router bits with car­bide inserts like their larg­er sib­lings have, by all means try them out and also let me know where you found them.

Fore­dom and sim­i­lar flex-shaft tools are an alter­na­tive to hand-held high speed drills. I am now using a Fore­dom motor with a Fore­dom H8 hand­piece for the free­hand work (see Part III) because the Fore­dom seems eas­i­er to con­trol than Dremels. If you want to use a Fore­dom for all steps of your inlay work you’ll need to fash­ion your own com­plete router attach­ment to hold a Fore­dom hand­piece (not easy) or to pur­chase the “pre­ci­sion router base” and cor­re­spond­ing spe­cial­ly thread­ed Fore­dom hand­piece from Stew­art Mac­don­ald.

You can use a padded bench vise or even sand­bags to hold the object that you are inlay­ing (usu­al­ly a fin­ger­board or peg­head already attached to a neck), or you can build a jig to hold it on a table­top. Pur­chase a stan­dard rub­ber sand­ing block from the hard­ware store, along with lots of 80, 100–120, 220, 320, 400, and 600 grit open coat and wet or dry sand­pa­per. A large mill file and a flat cab­i­net scraper are use­ful for lev­el­ing the inlays and filler with the wood in the final stages of an inlay project. Oth­er tools you might need include a very small chis­el for clean­ing inlay pock­et cor­ners, gravers and Laskin’s filler if you intend to engrave the inlay, and oth­er bits for the high speed drill as the need aris­es.

Staying healthy:

Con­trary to fre­quent asser­tion, nei­ther moth­er of pearl nor abalone dust is tox­ic. How­ev­er, the ultra­fine but sharp-edged par­ti­cles that result from grind­ing or saw­ing shell can enter the operator’s lungs and do all sorts of mis­chief at the cel­lu­lar lev­el, nev­er ever to be expelled no mat­ter how hard you cough. If you grind shell or saw lots of inlay and thus gen­er­ate lots of these par­ti­cles, lots of them can lodge deep in your lungs and could even­tu­al­ly cause seri­ous, even fatal, res­pi­ra­to­ry dis­ease. The trou­ble is that the thresh­old between minor and sig­nif­i­cant expo­sures undoubt­ed­ly varies with the indi­vid­ual, and no one knows where that thresh­old may lie for any­one. To avoid inhal­ing pearl dust you can use a NIOSH-approved res­pi­ra­tor, but first con­sult an occu­pa­tion­al health physi­cian for infor­ma­tion on med­ical clear­ance for res­pi­ra­tor use, and ask an indus­tri­al hygien­ist for advice on res­pi­ra­tor selec­tion and fit-test­ing to ensure that the res­pi­ra­tor actu­al­ly pro­tects you.

Hard­ware store res­pi­ra­tors may or may not work, depend­ing on the type of pro­tec­tion the spe­cif­ic res­pi­ra­tor offers and on the seal the res­pi­ra­tor makes with the operator’s face under a vari­ety of con­di­tions. Only an expert at fit-test­ing can ver­i­fy cor­rect res­pi­ra­tor fit, but I rec­og­nize that many will still opt for the hard­ware store approach. Half-face hard­ware store elas­tomer­ic res­pi­ra­tors should indi­cate HEPA (high effi­cien­cy par­tic­u­late air) or P‑100 fil­tra­tion and they should also indi­cate NIOSH approval. If pos­si­ble try the fit first by don­ning the mask with fil­ters in place, breath­ing nor­mal­ly for a few sec­onds, then plac­ing your palms tight­ly over the fil­ter car­tridges to block inflow­ing air. If you can still breathe the res­pi­ra­tor is not mak­ing a good seal. Try adjust­ing the straps before reject­ing the unit and also try a dif­fer­ent size of the same mod­el if avail­able, but if you don’t obtain a good seal the res­pi­ra­tor won’t pro­tect you. Also try each unit while look­ing in var­i­ous direc­tions, talk­ing, bend­ing over, and chang­ing to oth­er body posi­tions like you would real­is­ti­cal­ly expect to do when work­ing with inlay. If you opt for the less­er “mask” instead of a res­pi­ra­tor, pur­chase (usu­al­ly dis­pos­able) N95 masks that bear the NIOSH stamp. Do not use “dust masks” which offer no pro­tec­tion at all from the ultra­fine par­ti­cles. When you don the mask be sure to squeeze the met­al band around the bridge of your nose so that it makes a snug fit. Use the mask even if you cut only a lit­tle inlay. If you have facial hair beyond a mous­tache and no desire to shave you real­ly should con­sult an indus­tri­al hygien­ist because it can be dif­fi­cult to achieve a good res­pi­ra­tor fit for the hir­sute among us and an indus­tri­al hygien­ist can offer the best coun­sel on this prob­lem.

Using com­pressed air to blow the pearl dust away from the inlay dur­ing the cut­ting is poten­tial­ly a bad idea because even a slow and gen­tle air stream can aerosolize the dust right under your nose, and could trans­form a minor dust expo­sure (dust par­ti­cles released by the saw­ing) to a sig­nif­i­cant expo­sure (invis­i­ble clouds of dust). I have the same con­cerns about vac­u­um sys­tems, unless they are HEPA fil­tered at the exhaust (with an effi­cient pre­filter to avoid clog­ging the HEPA fil­ter). If the pearl dust from saw­ing actu­al­ly does obscure the work (it rarely has for me) I rec­om­mend that you use a small artist’s paint­brush to sweep away (gen­tly) the accu­mu­lat­ing dust.

Getting older:

Six­teen years ago I wouldn’t have dreamed of using an opti­cal mag­ni­fi­er to help me see the pearl I was cutting—magnifiers typ­i­cal­ly have crit­i­cal focus that means that being just a bit too near or far from the work results in a blur­ry pic­ture. Nowa­days at my slight­ly advanced age the choice seems to be between doing slop­py work or using a mag­ni­fi­er so I now use a stan­dard binoc­u­lar mag­ni­fi­er and have adapt­ed to the crit­i­cal focus with­out too much dif­fi­cul­ty. These devices range a bit in qual­i­ty and price—try read­ing fine print with sev­er­al dif­fer­ent units at var­i­ous dis­tances and see which gives you the least crit­i­cal focus com­bined with the sharpest image.

Con­tin­ue to Part II, Cut­ting Pearl…