FRETS.COM Presents:

Luthier Technical Q & A
© Frank Ford

At your service:
Michael Dresdner
Dan Erlewine
Frank Ford
Charlie Hoffman
Don MacRostie
Bob Taylor


To submit a question, just contact me and I'll pass it along. Give me your name, city and state (U.S.) or country so I can include them in the article, or let me know if you prefer to remain anonymous. I'll try to respond to all inquiries and post those that seem appropriate in this column (presuming we can answer them!)

Here's a list of topics, so you can jump right to them:

Clear Pore Filler

Glue for Broken Headstocks

Glue for Wenge and Bubinga

Flaming Maple

Hardening Fret Wire

Intonation and Saddles for 1920s Martin Guitars

Lacquer Tinting Colors

Lacquering and Sealing Spruce

Lining Material

Nickel Plating - How to Make it Look Old

Nut Position for Best Intonation

Protecting a Celebrity Signature

Refinishing a 1932 Martin 0-18

Restoring a 1908 Martin 0-17; Ethics, Style and More

Scale Lengths - Adding extra frets

Tolerances: What tolerances are allowable in guitar making?

Tuning Forks: anything besides A-440?

Vinyl Sealer, Shellac and Finish Adhesion

Waterbase Finish Crosslinker Proportions

QHello! I've got a question I hope you can help me with. A friend of mine approached me with a delicate work: Master bassist Billy Sheehan signed last week his white 1963 lefty Rickenbacker and he wants to protect the signature without harming it, so he can still play the instrument without worrying about erasing Billy's name. Which procedure/products would you suggest to use in order to accomplish the work successfully?

Alexander, Caracas, Venezuela

A Well, this can be delicate work indeed. If the finish is nitrocellulose lacquer (I presume that would have been the original finish for Rickenbacker in 1963) then you'll need to overspray the area to protect the signature. In order to get a nice clean job, you'll probably want to cover the entire surface with a clear coat of lacquer so you don't get a "feather edge" when you level and polish the finish. Because the lacquer solvents will be very likely to attack the ink or paint of the signature, you'll need to be extremely careful how you apply the new lacquer. It's usually possible to adjust the fluid control on your spray gun to allow only a light mist to hit the surface, so the lacquer is virtually dry as it lands. You can spray just the signature area in that manner to build up a bit of lacquer which will look rough and dry. Then, when you spray the entire surface with a normal wet coat, the new lacquer will melt this dry area without causing the signature underneath to run.

Before spraying, you'll want to "scuff" the surface to dull it completely with fine sandpaper, about 320 grit. Sand the entire area to be sprayed, getting as close to the signature as possible. This is an important step to promote good adhesion of the new finish. If the finish is a catalyzed polymer, then you'll need to spray or wipe a coat of shellac as an intermediate bonding layer. Clearly, if you're wiping, you'll have to stay away from the actual signature, but try to get in as close as possible with a cotton swab. A bit of acetone will be sufficient to test to see what finish is on the guitar. A touch with a cotton swab soaked with acetone will etch lacquer deeply and immediately, where it will have virtually no effect on catalyzed finish.

In any case, be sure to inform the owner of the guitar as to how risky this procedure is, so he'll understand if it doesn't come out perfectly!

- - - Frank Ford, 3/21/02

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QCan you give me a formula for adding the crosslinker to waterborne laquer in small quantities, like a 4 oz cup? Also, is the crosslinker really needed or will the finish eventually link anyway? What are the pros and cons of using the crosslinker? Normally I have not been using it, but I find the final finish remains softer than I would like.

Thanks in advance, Michael Turko, San Diego, CA

A There are two major categories of crosslinkers used with waterbornes (aziridines and carbodiimides) and they kick at different amounts. The cure time is the same with or without crosslinker. The crosslinker changes the molecular size, making it a tougher cured film. It is not about curing speed, but rather about what plastic you end up with once the solvents are gone. (Yes, in the formulator's vernacular all these dried films are plastics.) The crosslinker will give you a different, more durable plastic than the film you'd get without crosslinker.

Since you didn't tell me which you are using, I can't be much help except to direct you to use the amount that the manufacturer suggests. As for smaller amounts, simply do the math. There are 128 ounces in a gallon, and 32 in a quart. Whatever amount of kicker they instruct you to use for any given volume of finish, simply divide the ratio into whatever amount you care to mix. In other words, if they say, for example, to add 4 ounces of kicker to a gallon, that would be the same as one ounce per quart or 1/2 ounce per pint. If they say to add 8 ounces per gallon, that would mean 2 ounces per quart or one per pint. See what I mean?

- - - Michael Dresdner, 7/9/00

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Q I build and repair guitars in Bangkok, Thailand. A customer asked me to make a 36" scale length bass but I have only 34" and 35" fret scale template. I posted for help at a bass news group and Mr. Bill Sveglini replied and told me to contact you. Do you know anybody or any luthier stores who sell 36" or longer fret scale template? Your frets.com is very cool, interesting and very useful, I really love it.
- - - Thank you and best regards, Wachira Jinatune, Bankok

A Thanks for the kind words about FRETS.COM, Wachira!

If I need a longer scale, I use a little trick that works for me. It's a little tricky to describe, but here's how it goes:

To generate a scale that's one fret longer than the one I have, I measure the distance from fret #4 to fret #ll. Usually instead of actually measuring, I just set a pair of dividers to that distance. This now is the distance from the 4th fret to the nut. That is, I've generated a scale that's one fret longer than the original.

If you use this little trick on a 34" scale, you should come very close to 36" It can be repeated for longer scales, of course, but if you go too far, you're likely to introduce error.

- - - Frank Ford, 11/16/99

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Q I bought my first guitar kit recently from the Martin Company and spent all last weekend building dreadnought jigs and various front and back clamps. Needless to say, I am ecstatic with my new project. Additionally, I do woodworking as a weekend hobby, so I have access to a lot of stuff. My question to you, if I may, is what tolerances "over all" are allowed and acceptable for the guitar maker. I fully understand the concept of intonation. So saddle placement should be within a 1/64" or so. But nowhere has any of the literature mentioned anything about tolerances. Can you help me with this question? Professionally, I am an electrical engineer and I work for the Navy.

- - - Kevin Walker, PE

A This is an interesting question, Kevin. As an individual luthier, I work to the tightest tolerances I can handle within the constraints of my ability and the time I have for a project. Fret positions and the relative heights of frets, center joints in spruce tops, fitting of saddles, height of nut slots - - these are operations that very tight tolerances indeed, just a thousandth or two. The overall dimensions of guitar bodies, for example can vary by 1/8" without anyone noticing at all. In short, I use a sliding scale, depending on the relative importance and visibility of the parts in question.

- - - Frank Ford, 5/7/99

A This is the beauty of guitar making. The tolerances are very forgiving and I'd be hard pressed to put a number to it. It would be like saying what tolerances are allowed in spaghetti sauce.

The only dimensions that you need to worry about is in fret placements and saddle placements. Again, the saddle placement, in turn, is affected by string height and gauge. Get the frets right and "hunt," with something temporary, for your saddle location, checking it with a tuner, and you're all set.

The rest is just spaghetti sauce.

- - - Bob Taylor, 5/9/99

Say, Bob, that sounds like good advice for the individual luthier. You make thousands of guitars every year with some very sophisticated tooling and designs. How about letting us in on the kind of tolerances you need for that kind of production ?

A Well, then, Frank, if you want to talk to what tolerances we work then I'll say that we keep it real close on anything that we can. Bodies, well, mostly and up to this point the tolerances are visual, except for the location of the soundhole in relation to the neck joint. Even this isn't all that close....maybe a 32nd.

On the new guitars? The bodies have to be right on the money as far as top arch, top brace fitting, top and back alignment, and soundhole location. It's all tooled and the tooling is within a couple thou. The bodies are now constructed on CNC routers because we can't even make them by hand for a couple reasons. One, the fingerboard brace needs to be mortised into the kerfing WITH NO GAP....We simply cannot let the brace fall downward before it bottoms out. This can't be done by hand, so we use CNC. In addition that same brace ship-laps with the heel block shelf and this as well cannot be done by hand because the tolerance is a couple thousandths. Really.

The neck and the neck joint of the new guitar. Plus or minus a couple thousandths as well. Imagine inlaying both the fretboard (Fender neck style) AND the heel into the body with NO GAP. Imagine making a hundred a day of that joint and causing it to look as though it was glued on top of the body like a normal guitar. You can then imagine the tolerances requires. Even the finish thickness is calculated into the size of the neck and the heel portion that fits into the body receives no sanding and must be totally machined to perfection, or else...

But is that guitar making? Well, yes, it is for me and my factory, but not for a person who's a machinist and wants to make guitars at home and is wondering what tolerances are required, if you get my drift. To that person, the fret slots, nut, and saddle are truly about the only things that will expose his guitar as having bad tolerances to a player. The rest, if it's right or wrong is just opinion.

We put inlays in our fretboards with a .005 gap around them.....because we can. We used to have whatever gap we ended up with, because that's all we could get.

I'm sure this is interesting, even though probably not specifically helpful to the individual luthier.

- - - Bob Taylor, 5/10/99

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Q I'm building a relic of a 57 Stratocaster, and was wondering if you knew how to make new nickel tuners look old like the one's of 30 years ago. And maybe the bridge to.

Thank you so very much

- - - Michael


A There are two steps to aging metals. The first is abrading the areas that naturally wear from hand contact. You can do this with steel wood, Scotchbrite, or ultra-fine sandpaper. Second, nickel (and I assume they are nickel and not chrome) also corrodes a bit during contact with the acid in sebaceous (skin) oil. A soak in some medium-strong acid should do it. I would try muriatic acid (which is dilute hydrochloric acid) to start. You might also want to try oxalic acid -- at least a 10% solution.. Both are available in most any hardware store -- muriatic as a liquid and oxalic as a powder ready to dissolve in water. Oxalic acid is used as a wood bleach to remove certain types of stains and to rejuvenate wooden decks that have gone grey. Muriatic is used to clean plaster off of brick. That should steer you to the correct departments to find both in a hardware or home store.

- - - Michael Dresdner, 11/13/98

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Q I've looked many places to find an article on how to quilt or flame a maple guitar top, but haven't had any success. If you have any information on how to I would greatly appreciate it. Thank you.

- - -Mark Yerrington, Gilbertsville, PA


A "Flaming" is an ancient technique using a candle flame, waving it under, and depositing soot on woodwork to imitate the natural figure that occurs in maple. In musical instruments the technique is used only for the VERY cheapest ones, and these days is most likely done by silk-screen printing or with an airbrush. Maple treated in this way can look very much like the real thing from over 10 feet away, but lacks the iridescent sheen of real wavy grain, and usually looks pretty bad up close.

When a guitar is described as having a "flamed" or "quilted" maple top, those adjectives are referring to the natural figure of wavy grain that occurs in wood.

If you're still interested in learning the technique, you might go to the library and research the topic of "trompe l'oi" painting, or faux wood grain painting.


- - - Frank Ford, 11/8/98


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Q I despise messing with kerfed linings, especially trying to manufacture them. I have read about using laminated, unkerfed linings for the back, and individually glued blocks for the top. Is there any reason, acoustically or structurally, that I couldn't use laminated linings for both the top and the back? What type of wood would you recommend?

- - - Terry Wells

A OK, here come some heavy handed opinions:

1. The ONLY reason for using kerfed linings is that it is CHEAPER. Factories do that because by kerfing, they make the lining easily bendable and they cut out a lot of labor. Early Martin instruments had solid linings or lots of individual lining blocks.

2. It is simply not possible to affect the sound by using different material for linings, if they are of the same dimension.

3. Guitar players are so used to seeing kerfed linings that they assume solid linings are somehow inferior, in spite of the facts. ALL violins have solid linings, by the way.

4. Use any dang lining material you like. Most luthiers use mahogany, Spanish cedar or basswood because of ease of workability.

- - - Frank Ford, 10/2/98

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Q We have recently taken on a restoration project that may provide grist for your Q &A section. We recently bought a 1908 Martin 0-17 which is in terrible shape (I will post some photos on my web site tonight) It is my intention to restore it to the best possible playable shape. There are several questions which are raised which, although I am never lacking in opinions, are well worth a discussion and second opinion. What comes to mind:

1. The rib on the treble side is very badly broken and even more badly repaired. Pieces are missing. The question is: Do we replace the whole rib or do we patch it so as to retain some of the original wood (perhaps 40% can be saved)?

2. The peghead veneer has 8-10 rhinestones set into it, and will be badly scarred when they are removed. Do we replace the veneer with a new (albeit Brazilian rosewood) veneer or do we simply leave it (or touch up)

3. Do we reinforce the top (bridge plate) so as to permit use of steel strings, or do we leave as is.

4. The original bridge is gone, and the replacement is oversize. In restoring the guitar do we make an "oversize" bridge or do we make it the original size and attempt to restore the damaged finish.

5. Large sections of the wood around the soundhole are missing. Do we leave it as is or do we attempt to restore the original shape (size) of the soundhole.

It seems to me that each of these questions raise questions of both ethics of restoration, value of vintage guitars, players vs. collectors and, of course, issues of how to actually do the work. My initial thoughts on these questions is to lean towards the first option I have presented ¯ i.e. make it a usable instrument and worry less about total originality. It is my present thought that I will photograph the process of restoration and make it a special section on my own web site (http://www.hoffmanguitars.com)

- - - Charlie Hoffman, Minneapolis, Minnesota



A Well, Charlie, that's quite a job you've got hold of!

I agree with all your items, and I'd choose the first option on each of them, except the bridge replacement.

1. A new side is sure to be better looking than making a patchwork of the old one with so much damage.

2. The new peghead veneer is no big deal in my judgment, because the damage is not normal cosmetic wear; it's basically impossible to touch up that kind of damage.

3. The bridge plate is a matter for discussion with the owner of the instrument (in this case, I guess that's you) and is an opportunity for the luthier to help decide whether the guitar can handle steel or if it is even a priority. Personally, I'd go for steel stringing because this critter will undoubtedly sound best with steel. Maybe you can do a really artful job with the bridge plate when the side is off. . .

5. I think the soundhole should be fixed to keep this guitar from being any uglier than necessary.

4. I'd try to work with the original bridge size and shape.

In years past I replaced oversize bridges with oversize bridges. After all, the damage to the top finish had already been done, and it's lots more difficult to touch up finish than it is to make a bridge to cover it. These days, with the emphasis on originality of style, I'm replacing oversize bridges with standard ones wherever possible and suffering the touchup difficulties. I think the results look better that way. The only problem is that it's usually quite a bit more expensive. Now that these old timers are worth more money, we're able to stand the expense more often.

One more thing:

How about a French polish refinish job on the face to correct the soundhole and bridge area? What with all the work this guitar is getting, I think originality of style should take precedence over originality of condition. That is to say I don't think there's much point in worrying about whether the top is refinished when there's new finish in so many other places and the touched up finish on the face is likely to look like just that, when a sensitive French polishing will make things actually look more original, much as the new side and peghead veneer will look more original than a bunch of patches would.

Please do post this job on your website, Charlie, and we'll all check in to see the progress!

- - - Frank Ford, 8/7/98

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Q Would you happen to know how to dissolve what could be either white or yellow glue from a broken Les Paul headstock. It had broken again on the glue line. Seems to have a very shiny surface. Also, what glue would you recommend when regluing a broken headstock?

- - - Michael

A Well, this is a nasty piece of business. I'm assuming that the peghead isn't broken off completely. . .

It's really hard to get the old glue out of there. In fact, I generally don't try to get much of it out unless there's a lake of the stuff in the joint. Usually that meant poor clamping pressure when it was glued the first time

Water is the only solvent I know for white or yellow glue. Warm water will soften and mostly dissolve the stuff after a while, but it's hell to get out of a tight joint.

Problem is that white and yellow glues break down completely at a rather low temperature, for instance a hot parked car. They may "cold flow" as well, so I don't like to use either for a broken headstock.

I prefer to use hot hide glue for a nice, clean new break, but for a reglue job like this I'd go with cyanoacrylate for good adhesion to a dirty surface. It also has good cohesive strength and can fill gaps well.

I run in some of the thin viscosity stuff and follow with medium. Then, working fast as I can, I'll clamp up with waxed paper under the cauls, and try to clean it as I go. The superglue eats right into the lacquer, so there's touch up for sure.

- - - Frank Ford, 7/20/98

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Q I realized during the transition period of Martin changing from gut string to steel in the '20s, all Martins were using pyramid bridge. However, it has come to my attention that some of these Martins after 1922 or so, which are braced for steel string, some of them are fit with a level saddle but some with a slanted saddle. I have even seen a OM-28 made in 1930 which has a pyramid bridge but with a level saddle. Frank, in your opinion, will these level saddled instruments have problem in their intonations? One other possibility I can think of is - May be at that time when steel string are made standard which came with slanted saddle whereas people could special order them for gut string and those came with level saddle.

If the level saddled ones is going to have intonation problems with steel string, how does one correct the problem? Replace the bridge altogether? Fill the old slot with matching colored ebony and re-rout a new slanted saddle slot? Or leave it as is for the sake of originality? Please advise your thoughts.

- - - Jeremy, Canada


A Jeremy, it seems you've thought this one out! I agree with your observations on the old Martins. I think you may be right about the straight saddle for gut and slanted for steel. Also, I do know for certain that many of those 1920s Martins were ordered as Hawaiian guitars, and they were fitted with straight saddles and an elevated nut for slide playing.

Do they play out of tune? YES!

I try to keep things original if the condition or value of the rest of the instrument warrants it. Compensating the existing saddle helps a little. I have no problem inlaying and routing for a saddle in the compensated position on most guitars, but on pristine examples, it can be a more difficult choice. If I'm making a new bridge for a steel string Martin, I try to get the saddle in the position for best intonation.

The other day I was called on to replace the friction pegs on a rare old banjo and had to drill it to fit geared pegs. After advising the owner about the originality issue, I heard him say, "Well, this thing sat around for a hundred years and it's in perfect condition because nobody could PLAY it!" A good point to remember.

I like to give the option to the owner of the instrument, but if I have my choice, I'll use the best compensated, slanted saddle position I can manage without compromising the bridge pin holes. After all, a really good replica bridge should be basically undetectable, so you can always go back to the original style.

I saw a fine job T. J. Thompson did a few years ago. He converted a pyramid bridge to left handed with a slanted saddle and didn't change any part of the bridge. He inlaid the slot with an ebony filler piece, but didn't glue it in. Then he made a curved bottom saddle that just sits on top of the bridge and is pinned in place by the downward pressure of the strings. Take the strings off, and both parts come right off as well so you can put the original saddle right back in! I like the spirit of that approach; I'd want to make sure the owner of the guitar is ready to handle the complications of stringing, etc.

Bottom line is that it's always going to be a judgment call. In my opinion, the well informed owner should make the choice. I don't think we should dwell on originality so much. These guitars are beginning to own us, if you know what I mean. . .

- - - Frank Ford, 7/18/98

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Q I have come into possession of a 1932 Martin 0-18 that has been the recipient of some mistreatment and some bad repairs. It is in need of some restoration work to bring it back to playable condition. I've been building guitars for several years now and I think that I am ready to tackle a restoration of this magnitude.

I need some advice concerning the finish. The guitar was poorly refinished at some time in the past and given a matte finish. I would like to restore it to a finish as close to the original as possible but I do not want to do any more damage to the instrument than is necessary. I have thought about using lacquer reducer to try to slowly dissolve and remove most of the old finish and then shooting it with a couple coats of lacquer.

I would prefer not to touch the finish on this guitar but the damage has already been done by the original refinisher. Could you offer some advice on how to do this with the least damage.


- - - Mark Middleton, Carlisle, PA. USA


A Well, sounds like you have a dandy candidate for refinishing. It can be a bigger job than you've outlined, but in general I agree with your plan.

I'd use regular paint remover to strip the old finish off. Because it's strong stuff, you have to keep it strictly off any celluloid binding or pickguard. Paint remover works well in this application, and the resulting surface can certainly stand a light amount of sanding, say with 220 grit.

But here's the big dilemma. The new coats of lacquer are certain to have a serious effect on the celluloid parts of the guitar. In a few years the binding is likely to crack all over and the pickguard will crack as well. I've seen so many refinished instruments with these serious cracks, I figure it's going to happen for sure. So what to do? I think the best case is to remove and replace ALL purfling and binding. I'd stop short of the soundhole rings, only because of the difficulty in removing them.

With the neck, bridge and pickguard off (a good idea whenever refinishing a Martin) you can then give the instrument a really fine finish over the new celluloid. After it's all over, you might be able to install the original pickguard on top of the finish as though it were a new one, or you might simply make a new one with beveled edges to mimic the under-the-finish look.

Now, I'm not saying that you can't add finish over old binding, but simply that I've seen a LOT of cases where the binding developed cracks every 1/18" until it fell off in tiny chunks. So, as a result of the increasing value of these old guitars, I'm replacing binding if I refinish with lacquer. I've seen this horrible cracking occur within a year or so, or take longer to develop. Unfortunately, this is something I had to learn the hard way. . .

If you were to use a non-lacquer finish, such as shellac French polish, you'd avoid the celluloid deterioration, but you'd have an instrument with the characteristically delicate shellac finish. This would be my first choice for a guitar made in the 1920s, and I don't think it's too much of a stretch to use shellac French polish on a 1932 0-18.

If the finish is sound enough to be leveled and not stripped off, then you might consider overcoating with the shellac French polish to give the sort of gloss you'd like. This touch up technique can really improve the look of an inferior but sound finish.


- - - Frank Ford, 7/17/98

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Q I have been using nitrocellulose lacquer on spruce for 25 years and am only recently experiencing some new problems. I've asked around and a lot of luthiers are seeing it too. Why it seems to have surfaced only in the last couple of years, I don't know. When I spray spruce tops the lacquer sinks in on some of the grain lines leaving irregular lines several inches long in various places on the top. When you spray over these, the lines continue to reappear. It looks like the lacquer is being dissolved by pitch or something coming from the wood surface. Spraying a coat of shellac first helps, but does not eliminate the problem. I've also tried fisheye killer, vinyl sealer, and washing the surface with naphtha or lacquer thinner, to no avail. The only change I've made in the last couple of years is a change to HVLP. Otherwise, I'm doing everything the same. The current lacquer I use is McFadden. Got any suggestions?

- - - Bob Gleason, Hilo, Hawaii

A There are two simple answers, and which you choose depends on which fits your manufacturing scheme. You can either massively extend the internal and final dry time prior to buffing, or switch to an inert, highly cross linked sealer before applying the lacquer. The natural choice for this sealer would be polyester. The styrene monomer in polyester resin will allow it to absorb deeply into the wood. Once it chemically cross links, it is inert and stable. You can then top this with lacquer and it will stay put without shrinking. It will also allow you to buff the lacquer sooner and may substantially reduce the number of coats of lacquer you need to apply.

Though this technique is common in other areas of the wood industry, its usage in guitar work was more or less pioneered by Dana Bourgeois, and he should get the credit for having the courage to try it.


- - - Michael Dresdner, 7/14/98

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Q Can you give me some recommendations for colors or pigments I can use for lacquer touch up work?

A Speaking generally, I would keep a minimum of two types of colorants on hand if I were repairing guitars using lacquer. I would probably keep both in the same four colors you mentioned. The colorants I'd choose are:

1) Trans Tints from Homestead Finishing Products. (440) 582-8929 These are pre-dissolve pure dyes with no additives or extenders that are cut
into a glycol ether base. They are highly concentrated and mix easily into water (for use as a dyes stain on raw wood) or into a variety of solvents (for mixing into shellac or lacquer as a translucent shading stain). Homestead sells them in 2 oz dispenser containers that allow you to add them one drop at a time. They are also available in larger volumes.

2) UTC's : To cover my pigment color needs, I'd keep a set of UTC's -- Universal Tinting Colors. Make sure they are miscible in whatever you plan to use as your mixing medium. Not all UTC's are alike. There are any number of sources for these including several mail order houses and most paint stores.

- - - Michael Dresdner, 7/8/98

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Q I have noticed that Taylor guitars seem to play especially well in tune up the neck. A friend suggested that you may be reducing the distance from the nut to the first fret to allow for the differential string stretch in the lower fret positions. If this is true, can you please tell me by what amount do you reduce that distance? I am building my first guitar and would like to take any opportunity I can to avoid tuning problems.

- - - Michael, San Jose, California

A Yes, we do reduce the distance from the nut to the first fret and we do it by the width of the fret saw kerf plus about .003 to .004" for clean up later in the process, for a total distance of about .016".

A luthier could argue both ways about where to cut the nut slot. One argument is that you should cut down the middle of each location, including the nut location. Since the fret sits in the middle of the slot (ours is .024") but the nut sits at the front edge of the slot, you effectively chop off about .012" with this line of thinking.

Others will argue that the nut space should be moved back by one half the kerf of the saw blade to compensate.

Both arguments make sense. I have no theory that is intonation based, and as a matter of fact I did it in the way that I explained simply by not thinking it through completely. I was lucky, because the method I chose, quite by accident, works very well. In fact many of the intonation gurus have arguments as to why one MUST cut off distance at the nut, so I guess I'm not so dumb after all.

- - - Bob Taylor, 7/6/98

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Q I recently finished a course in guitar building, during which I built and set up a fingerstyle guitar with a koa body, mahogany neck and spruce top. I sealed the entire instrument about one month ago with the vinyl sealer that supposed to go under nitrocellulose lacquer. I understand that I can't spray nitrocellulose lacquer over this sealer because of its age.

I plan to sand down to the wood and reseal the surface with freshly made shellac. Will the shellac adhere to the vinyl sealer well enough so I won't have to worry about adhesion in areas where I don't really get all the vinyl sealer off? Can I simply use the shellac as an intermediate coat and avoid some sanding? Does shellac make a good undercoat for the water based clear finishes?

- - - Randy Harris, San Francisco



A Yes to all three of your questions. There is no need to sand the vinyl OFF, simply sand it to rough it up. This increases the surface area and allows the next coat, whatever it is, to adhere better. Shellac has such wonderful adhesion that it sticks to darn near anything, even glass and vinyl. Make sure the shellac is FRESH and DEWAXED, otherwise it will not act as a "tie" coat that ties together the vinyl and lacquer.

For the record, when you let vinyl sealer sit too long, the common method of dealing with it is to scuff sand (220 grit) and respray a very thin coat of vinyl, since it WILL adhere to itself. Then spray your first coat of lacquer within 45 minutes of when you sprayed the vinyl. Once a coat of lacquer is on, you can leave it as long as you want before subsequent coats, since lacquer will always redissolve (hence stick to) itself.

Michael Dresdner, 7/6/98

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Q I'm currently building a bass for a friend, and the neck is to be laminated out of 7 pieces of wenge and bubinga (like a Warwick thumb bass).

The problem is what glue to use?

I tried Titebond I (yellow) on some scrap and it didn't hold at all well. I've managed to get some West Systems epoxy which was recommended, but I haven't had a chance to test it yet. Do you guys think this would be the way to go, or is there something better?

- - - Andrew McWhirter, Sydney, Australia


A There is no question that the West System epoxy will work, and since it is free of water, it is arguably the best adhesive for the job, albeit the most expensive and messiest to use. There is a growing movement here in the States to avoid water when gluing up multiple piece necks. Some factories have told me they notice the difference in the amount of movement a neck experiences at setup even when the fingerboard alone is glued up with epoxy rather than water based adhesive.

However, it would be a disservice to Titebond if I did not also mention that it SHOULD have worked, and I have many times worked with both Wenge and Bubinga with Titebond and experienced no problems whatever. Are you sure the adhesive you used was fresh and viable? It has a rather short shelf life (18 months at most) and does NOT do well going through temperature changes, either hot or cold. Being stored in even slightly elevated heat (such as in the hold of a ship going to Australia) would dramatically decrease its shelf life.

- - - Michael Dresdner, 7/6/98

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Q Where can I find tuning forks in other keys and lower pitches than the commonly available A-440 and guitar first string E?

- - -Mike Papciak, Berkeley, CA

A Piano tuners still use forks for tuning. American Piano Supply (973-777-3600) carries a chromatic set of 13 from C261.6 to C523.3 which also can be purchased separately. There are two other piano supply houses which I am not able to get their phone numbers: Schaff in Chicago, and Pianotech in Detroit.

Option two is to go to one of the scientific (expensive) firms that make tuning forks for optical research, and get a custom fork. Electro-Optical Products (718-776-4960) or Jonard Industries (914-793-0700).

Option three is to make your own tuning fork. One can be made from aluminum and tuned by shortening the length of the forks. Aluminum can be band sawed or milled, and will vibrate quite well.

- - - Don MacRostie, 3/25/98

Additional comments from a FRETS.COM reader:

I've made a few tuning forks out of aluminum, and also tuned a few vibraphone sets, and I have one important piece of information to pass along to other people who might attempt stuff like this.After you've cut the forks shape, you can raise it's pitch a little at a time by taking metal off the ends. I suppose you could also lower it by taking metal off the bottoms of the tines too, but I never tried that. The problem with aluminum is, it changes pitch drastically with temperature, and it's pitch will be a lot (lower if I remember correctly) when it is still hot from grinding. Even hand filing will heat the metal enough to change the pitch. So, each time an adjustment is made, it's important to return the fork to room temperature before measuring it's pitch. By the same token, an ice cold aluminum fork that's stored in a bag and carried through a freezing city like NY for twenty minutes will come out way off pitch and should be warmed in the hand before using to tune up with. I carry even my steel A=440 fork in my shirt pocket when I'm going to a job in cold weather.

Doug Westlake, 4/16/05

 

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Q I build classical guitars with backs and sides of rosewood and wenge. I'd prefer to use a transparent filler in the pores. Can you recommend materials or techniques? Currently I'm using West System epoxy with the 207 special coating hardener they recommend for finishes, but it still takes me 2-3 applications to get a complete fill. I heat the wood before applying the epoxy, so that it will draw into the pores as it cools. My finish is shellac French polish, and I don't want to fill with the finish because of the time and effort involved.

- - -Brian Burns, Palo Alto, California

A The most common (and fastest) clear pore fillers are the two-part polyester coatings, either chemically cured or UV cured. They will easily fill in just one squeegeed application. However, polyester will not always cure over rosewood, so you must first seal the rosewood with a isolator. Look for a material called "Isolante" or something similar -- it will be a two-part polyurethane. Seal the rosewood, then switch to the polyester as filler. To make it fill better and be easier to handle, thicken the polyester with glass beads or cellulosic thickeners. You can buy these at any marine supply outlet. (In fact, Gougeon Bros, the company that makes the West System epoxy you are currently using sells both glass bead and cellulose thickeners -- both of which will also help your epoxy mixture fill better!) You can generally add at least 10% filler material without loosing clarity. Experiment on scrap first to see if you like the appearance.

- - - Michael Dresdner, 3/26/98

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Q When I replace the frets on an old Gibson mandolin, I notice that the new ones wear out very rapidly. The manufacturers tell me that the fret wire I'm getting is the hardest available. Is there a way to increase the hardness by heat treating this modern wire?

- - -Luke Wilson, Grass Valley, California

A Yes, but it is not a good idea. The hardness of fret wire is a balance of workability vs. wear resistance. Softer fret wire is easier to "set" into the slot, while harder wears longer. As in all of life, there are tradeoffs. Unless you are well versed in metal hardening, tempering and annealing techniques (in which case you would not be asking this question) you are likely to make more trouble for yourself than you eliminate.

- - - Michael Dresdner, 3/26/98

A Generally heat treating to increase hardness will also make metal more brittle and less flexible. I am not sure that brittle is a problem, but decreased flexibility might make it very hard to get a clean fret job. I could envision the need to have the wire pre-curved to precisely the correct curvature, and still have problems with fret ends not seating well. I assume that you have done fret work with the super jumbo fret wire which is very stiff and have a good idea of what I am thinking here.

- - - Charlie Hoffman, 3/36/98

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