REPAIR AND BUILDING TECHNIQUES

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Question:

As we all know, a guitar that has been played for a few years sounds better than when it was new.   Can anyone explain why?  Does anyone know if a guitar needs to be played to break in, or will sitting there for a few years also make it sound good?

We know that the wood and finish age and that this improves the sound, but is there more to it than this?

Answer:

In my experience new guitars sound 'stiff' when you first fire them up.  If you play them steadily, you can year them come to life quite dramatically in the first few hours after they are first strung.  They seem to develop quite quickly over the first week or so.

That first few days tell me a lot about the individual instrument.  I've found that if the guitar is very 'dry',  or treble-heavy at first,  it will be OK;  in all likelihood the bass will catch up in a day or two.  If, on the other hand it is very bass-heavy right off the bat,  I'm probably in trouble.  I've found that very few of them develop much real treble or clarity up the neck after the initial break in period.

Back in the 1960s it was popular to sit your guitar on a stand in front of a large stereo speaker and crank the system up.  That supposedly made the guitar vibrate while you weren't playing it.  I suspect that it is very good for a guitar to be played a lot, to get all the little bits of wood used to being a guitar and used to working together but I am not aware of any honest data proving the point.

They also respond much differently in dry or wet weather.  I've found that when the humidity drops and the top loses the moisture it has been accumulating all summer they tend to loosen up and boom.  In very humid weather (over a 3 day or longer period),  they may tend to get a bit muffled or stodgy.

When it comes to hard and fast rules about the voices of guitars,  I don't think there are any.  This is why it makes sense to try a number of guitars and pick the best one rather than ordering one blindly from the internet!

Question:

Hey GuitarAttack…can you make me some double cream coil humbuckers?

Answer:

Sorry…DiMarzio trademarked the use of double cream coils in humbucking pickups.   I know for a fact that Bill Lawrence, Carvin, Gibson, Mighty Mite and Seymour Duncan all produced them at one time or another.  The original Gibson PAFs appeared by chance as the black dye used in the plastic was in short supply in the late 50's.  Remember -- at that time all pickups were made with covers and the last thing anybody worried about was the color of the bobbins!

Question:

How do you take care of white spots that occurred from Cyanoacrylic (CA or super) glue use on a lacquer finish?  Do I need to remove the CA?  Lacquer topcoats don't melt it back.

Answer: 

Some suggest MEK…this is a very dangerous chemical.  Others recommend acetone, which is known to dissolve CA glue.  If you already have lacquer over it, it may be too late to fix the CA without stripping some lacquer.

 We do not recommend using MEK for anything…it is a hazardous chemical best handled in labs by folks in white HAZMAT suits! 

Question:

I've a question for the many french polishers out there.  I'm cutting some 2 lb. orange shellac from flakes and am facing a problem with dewaxing.

I've cut 5 batches now using the same method and am getting very inconsistent results.  What I've done is filter it (3 times) through a paper medium and while it does seem to darken the shellac it still appears pretty murky and cloudy.   Of the 5 batches, the remaining wax on 2 batches settled on the bottom in 3 days or so.  The other 3 batches just won't separate (it's been more than a week).  Don't know why.  Might have to discard the whole lot.

Does anyone have a understanding of the problem?  Is filtering the right way to go?  Anyone have a trick for dewaxing that he/she can share?  Is temperature a factor?

Answer:

I've heard (but not experienced) that wax can be precipitated by popping the dissolved shellac in the freezer part of your refrigerator long enough to get it all cold. Then it can be filtered.

Throw out the orange shellac -- use the bleached or super blonde shellac. The orange shellac is a poorer quality shellac compared to the blonde shellac.  It is more refined than button lac, but less refined then Blonde.  In my experience I have noticed that orange shellac produces a softer, less durable finish. It is great for furniture but not for instruments.

The biggest determinant I've found for a good shellac job, after the initial quality of the material, is freshness.  It really helps to keep the unmixed stuff in the 'fridge, too.

A last tip: to mix up shellac, tie the proper amount up in a little cloth bag, and suspend it near the top of the jar of alcohol. The solution, being heavier than the solvent, tends to settle, and pushes the purer alcohol to the top. The circulation speeds up the process a lot, you don't have to stir up the thick goo at the bottom of the jar, and the bug parts and stuff are all filtered out in the 'teabag'.

Question:

Does scale length have an effect on the over tension and playability that a set of guitar strings has on a guitar. (a Les Paul with 10's is similar to a strat with 9's)

Answer:

Yes. At constant pitch, tension is proportional to length. The basic equation for the frequency of a vibrating string as :

f =((F/u)^0.5)/2L

where:

f is the frequency

F is the string tension,

L is the string length, and

u is the mass per unit length of the string.

Question 2:

What about the extra lengths added to the overall string length, say for instance the distance from the ball end to the bridge and from the nut until it meats each tuning machine?

Answer 2: 

That length won't influence the pitch of the string between the nut and saddle, but it will influence tuning, since a music string is real instead of "ideal", it will stretch a little when tuned. As you add more string length on either side of the nut and saddle, you are adding more string to stretch. This means more cranking to get to a given change of pitch, and also a little less "definition" of the point in your adjustment that gets you right on pitch.

The difference that is there, is feel, or "perceived" tension.  If  there is more string length beyond either the bridge or the nut, or especially both, the strings will have a softer feel, because the string slides over the nut & the bridge, & the longer the string, the easier it is to bend, because it has more length to stretch, but the tension is the same for the same pitch, regardless of length.

Question:

I remember seeing something about spraying nitro over tung oil, using an intermediate coat of shellac to improve adhesion to the tung oil surface.  Will it work?

Answer:

Assuming the tung oil has completely dried, you should be able to wipe on a thin coat of shellac.   Shellac will stick to just about anything.   Then you should have an easy time spraying   lacquer over the shellac.

I suspect the problem is more one of the tung oil swelling and poor adhesion and orange peel of the lacquer (on oily finishes).  What I've done (lacquer over enamel) is shoot a thin coat of lacquer, then let that dry completely. Repeat again.  Then things should be pretty stable unless you drown the finish.  Just keep an eye on it and go slowly at first.

Question:

I'm working (slowly at least) on a Les Paul style solidbody.  I want to do a natural binding ala PRS on the maple top.  I understand the basic process (mask the edge, apply dye, remove the tape, seal the whole thing etc).  My question is how to get a uniform line on the top surface and not have bleed under the tape.  3M makes fine line tape and I've used Scotch transparent tape before also.  How do you get the tape to bend around the corner without creasing?   What width is used (3/8" as one piece or 2 pieces of 1/8")?

Answer:

Mask the top, leaving the "binding" exposed.  Clear coat the "binding", this seals and protects it from the top stain. next, remove the masking, color your top as you would like, then use a single edge razor blade, held at a 90 degree angle to the top, and use it like a scraper to expose the very narrow edge you need on the top. Clear coat the whole thing and buff.

Try using black electrical tape, the el-cheapo stuff from the 50cent bin, for your masking while spraying the tint coats, either onto the wood or in the lacquer mix. It is very flexible and can make the curves. You can cut it with an Exacto knife to get thin strips. You need to mask, shoot and get the tape off the next day because it will slowly creep and  un-mask itself, but it is really great at rejecting finish/tint when it is down new. 

Question:

How do you finish your guitars, do you put on the neck and bridge and then buff out the lacquer or do you buff out the lacquer then put on the neck and bridge. If you do the first how do you get up and around the edges of the neck and bridge?

Answer:

Most makers polish the body and neck before joining them and before gluing on the bridge.  This is not uniform.  Neck and body finished and buffed separately, then neck attached and bridge glued. 

Question:

How do you make homemade radius blocks for sanding necks and frets?

Answer:

Technique 1. I made a set with Bondo.  Start with a wood blank the size you want and attach a couple of runners along the edges that stick out about 1/4".  It should now look like a sled.  Then I put a piece of 1/8" masonite in a vise, squeezed it until it formed the appropriate arch and covered it with waxed paper.  Finally, I mixed up a batch of Bondo and smeared it between the runners on the block.  Make sure to get it smooth or there will be voids on the completed surface.  Squish it down on the bent masonite and let it dry for 15 minutes.  Cut off the excess with a knife before it gets too hard and later sand the sharp edges.  That's it.  Elapsed time is about 15 minutes.  Bondo is pretty stinky so use the usual precautions. 

Technique 2.  I have made radius blocks by casting over a purchased radiused fretboard blank. What I do is lay the blank on a plywood surface, cover it with a sheet of aluminum foil, then nail down some 1x1's around the blank, framing it so that I could pour resin in, at the same time pulling the foil down flat and tight over the curve of the blank. Then, pour in polyester resin with some pre cut fiberglass strips, just to fill up some volume and reinforce the casting along its length, I poured the resin about 1/2" deep, allow to cure overnight, knock away the 1x1's, peel away the foil, file away any edges where the resin seeped, and you got yourself a full wide fretboard length radius block.   Cut them into smaller hand sanding blocks, or, use as a long clamping caul.  I've tried this with epoxy and the result was way too flexible, maybe it was the type I used, but the polyester works great. Make a selection of blocks based on all the radii that you can buy prepped blanks of. 

Question:

I have removed the fingerboard of a double bass and I'm about to reglue the fingerboard. The fingerboard was glued with a PVA-like substance and I want to reglue with hide glue. How can I get rid of the remaining PVA?

Answer:

If it's a "Titebond" type glue just douse it with alcohol, let it sit for a few minutes or so (add more alcohol as it evaporates) then it should be soft enough to scrape off. 

Question:

 A friend of mine wants to clean his fingerboard of gunk. He must have dirty hands. He has two guitars, one with a maple board, one with a morado board.  I told him Naphtha. I generally don't keep my guitars long enough to have to clean them any more!  I'm wondering if anyone else has any other favorites for cleaning fingerboards. I don't think he has much use for a quart of Naphtha other than to clean this one fingerboard.

Answer:

Technique 1.  Take the strings off, get and old toothbrush (not his mom's) and spray fantastic on the brush (NOT THE FINGERBOARD!)  brush about 5 or 6 frets at a time vigorously, then wipe dry with an old cloth.  Take a old cloth made of T-shirt material and wrap index finger in it and dampen (not wet) with lighter fluid and rub vigorously.  Then take clean cloth and wipe dry and move on to next 5 frets.

Technique 2. Some use a single edge razor blade, and avoid the solvents altogether. A little of the extra-fine Scotchbright gets what ever's left over.

Technique 3.  Formula 409, the supermarket ammonia all-purpose cleaner, does a great job cleaning fingerboards. Much safer than naphtha and in my experience more effective (nothing beats naphtha for removing tape residue and other gummy things from lacquer finishes though).

Question:

I have a Epi archtop with a sunburst finish and a thick, gloppy coat of clear (polyurethane?) finish. is there a way to take some or all of this finish off without effecting the sunburst stain? I am experienced with lacquer finishing but know little about polyurethane.

Answer:

Removing the finish will require restaining, unquestionably. The finish may be entirely done in shaded paints with no actual staining of the wood.  This what you hope for most.  If you try to use any solvents to remove the finish, you're certain to cause some staining in the wood, so it'd be MUCH preferable to sand off the finish instead of trying to chemically strip it.

I took the finish off of a cherry Epiphone archtop last summer. The finish is made up in layers of this clear stuff that makes it look "deeper", then I hit a matt red colored layer. If you keep sanding (for a long time as this is the thickest layer), eventually you'll get to a layer that is just a dull color. Mine was duller red compared to the first red layer that I hit. When you get to the point between the first red layer and the second layer, you'll see a kind of white shiny ring of a layer between them. The second colored layer can potentially be sanded, but once that layer is gone, I got down to a wood color so you have to be careful. Underneath that wood there is still a bit of clear coat.   So if you really wanted to do it, you could probably remove all the outer layers of finish and get a thin sunburst finish, but it will be dull like acrylic paint. I am not sure if the sunburst is finished differently though.   It took me maybe a week to sand it all down. I heard that a heat gun will work in removing the finish. As for strippers, even aircraft stripper didn't work on mine.

I'm assuming that the Epi that you're referring to is one of the newer Korean ones. The finish on these, as I understand it is a catalyzed polyester and is basically a very hard plastic that is usually between a sixteenth and an eighth of an inch thick.  There is no sensible way that I know of to remove any or all of this stuff without making big mess and you'd end up spending more time on it than any guitar is worth!

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