Current Fingerboard Inlay material?

[jps]

...I prefer the look of the late 50's and modern material over the sparkle look of the 60's. To me, the sparkle looks just too flashy. I do prefer the full width though. JKC

Then I suppose you like these?

[jingle_jangle]

Seems to me almost all the strength comes from the laminated maple and walnut, not the rosewood on top, but I'm really guessing. I'm guessing JH doesn't answer these types of questions anymore, so if anyone else has some info, much appreciated.

I always thought it was just a style change.

Thanks in advance,

JKC

Without the fretboard, the neck is a very thin (front-to-back) "E" channel, with two rather deep and wide channels cut into it for the truss rods. It's amazingly flimsy-feeling, especially in the case of a bass. Gluing on a fretboard makes it into a tubular cross-sectioned structural member which resists both bending and torsional stresses.

I've got a pair of identical '67 425Ss. Right now, both are stripped and waiting for finishes. One also needs a fretboard, so it's an open channel as described above. The difference in rigidity between the two is an amazing thing to experience. The one with a board can easily withstand the 130 pounds of force (approx.) that is put on it when it's strung and tuned to concert pitch. The unboarded one could not take even 20 pounds, and grasping the headstock in one hand and body in the other, it would be possible to twist the neck and probably splinter it with my bare hands.

I've never done any real testing to be able to demonstrate the superiority of one inlay style over another, but JH has stated many times that the later inlay style is superior to full-width inlays, in terms of strength.

[jcreasy]

Yep. That is what I've been told. Again, I'm not a luthier but I do work with wood on a regular basis. I had forgotten about the truss rod channels.

OK... Next question. When I do get some money set aside for fun stuff, I was going to have my inlays expanded. Should I not do that? Mine are pretty run of the mill JetGlo 360s from the early 90's but they really are important to me. Maybe I should just leave well enough alone. Paul? What say you?

As for the African or European swallow... I don't know that!

[teb]

Any piece of wood is going to be stronger and able to bend back and forth with less potential damage whole than it will be with slots or depressions cut into it. The bigger the voids, the weaker the piece of wood will be. Fill those slots with a similarly non-compressible material and you create sort of a one-way strength situation. It will resist forces in compression quite well - where in this case the inlays just need to resist being crushed (like the force caused by string tension and neck bow on a fingerboard). Bend it back though (like really cranking your truss rods, for example) and things change dramatically. The inlay would now be in tension and the bond of the inlays to the sidewalls of their slots as well as the sheer strength of the lamination of the inlay to the fingerboard are in danger. The inlay-to-sidewall bond is essentially a small butt joint and not very strong. The combination of polyester resin over paint in this case makes the bonds even weaker as it really doesn't stick well enough to be taken seriously in terms of composite constructions. In this type of tension/back-bend situation, the inlay is no longer contributing strength and the slots cut into the wood come into play and weaken the fingerboard.

I have a couple test RIC-style inlay samples that I made using cunks of bubinga, so I bent one to see what happened. It's 5"long by .25" thick and 1.75" wide with two full-width shark-fin inlays in slots cut about 1/3 of the way through. In compression (like neck bow from string tension) I couldn't apply enough force with my hands to even really bend the piece. Back-bending it and putting the inlay surface in tension though, was a different story. Without much trouble, I was able to bend it enough to hear the inlays crack away from the walls of the slots. Bubinga is pretty tough stuff though. By holding one end down on the edge of a bench, I was able to lean hard on the other end (inlays in tension - inlay side up) and eventually hear wood fracturing, but it took a lot of force. Flipping it over and bending it the other way (inlays in compression - like string tension) it was still stiff as a brick. On a fingerboard-length piece, the additional leverage would reduce the force needed and the piece would bend in both directions (and eventually break) much easier, but the characteristics of how the inlays respond to being put in tension or compression would be the pretty much the same.

Your mileage may vary, but my conclusion is that as long as you avoid situations that would cause outrageous amounts of neck back-bend, full width inlays with the stress from string tension and playing primarily in compression, pose no serious danger to the strength of the neck. Walk into a wall and bend the headstock back and it might be a different story, but I think you would have to hit it pretty hard and at that point the inlays might be the least of your problems.

[rickfan60]

The full width inlays do weaken the neck. The inlay spaces are cut pretty deeply into the fingerboard. As Paul said, a Rickenbacker neck without the fingerboard is very flimsy. If you take away the stiffness of the fingerboard you are not left with much.

During the 75th anniversary celebration I had the chance to talk to Richard Burke about the changes in inlays over the years. He developed the current inlays technique and had lots to say about the old ones. He said they would often explode (his word) out of fingerboard during the buffing process. He told me that if you look close the edges of the older inlays on some instruments you will see where the wood had to be reparied after a blow out. Jeff Scott has what appears to be just such a repair on his 4005WB.

[jingle_jangle]

I've not seen any engineering-type tests on this, and would love to see the numbers on strength on old vs. new style inlays.

There are some interesting things happening here, regarding the method of making the inlays, both old and new.

The old inlays "exploding" out of the fretboard is due to two things:

1. Depending upon the degree of oiliness of the fretboard wood, the adhesion of the inlay backup paint to the sides and bottom of the inlay recess, can be either good or not so good. The sides especially are in question here, as oily tropical woods like bubinga, teak, some rosewoods, purple heart, vermilion, padauk and others, exude their oils more from the endgrain than along the face. (In the '70s, I had stacks of padauk that had been fresh-cut and left over a weekend, actually growing mold on the end grain, due to the oil being a good growth medium for fungus). Oilier wood discourages proper adhesion of paint.

2.The old full-width inlays are polyester resin, just like the new ones. PE resin shrinks as it cures, average about 2-3%. PE resin does not adhere to paint very well at all; the styrene monomer which is its major component by volume will attack and soften paint films--including some cured polyester paint films, before the PE resin can fully crosslink. This means that at best, the inlay adhesion to the backup paint is less than ideal.

3. If a resin batch is mixed "hot" (i.e., with more than the recommended 2% [by mass, not weight or volume] MEKP catalyst), it will give off more exotherm (heat caused by chemical reaction), which in turn, causes excess shrinkage of the inlays. In my 35 years of working with PE resin, I have seldom seen workers mix it accurately, and the tendency is to over-catalyze.

The above conditions can cause the inlays to, upon fully curing and shrinking, pull away from the sides of the recess. They will also lose a good deal of their adhesion to the bottom of the recess. The buffing process heats the inlays, and the type of sideways force exerted upon the neck of a guitar or bass, can in some cases (rarely) cause the inlay to pop out. The term "explode" sounds really more violent than it is, as it's the rotating buffing wheel that accelerates the inlay, and guitar buffing wheels operate at 750-800 rpm. The wheel could theoretically catch the edge of a full-width inlay easier than a centered inlay surrounded by wood, although the presence of binding on these deluxe instruments would make this an exception rather than the rule. However, the fact that the inlay goes all the way to the edge of the 'board, and is capped by a thin sliver of binding (usually less that .020" or .5mm) means that a lot of buffing heat is transmitted to a full-width inlay.

I have seen Ricks with the new-style inlays, in which those inlays have shrunk and lost their adhesion over time. So this issue has not really gone away, nor is it likely to. Nor would I want it to--these are the most gorgeous inlays in the business, and another reason that Ricks are so special.

[rickfan60]

That sounds reasonable. Richard did say that he had to watch over shoulders to make sure the workers mixed the resin correctly. Also, there is a bit of an art to swirling the pearl toner. It can look good when the resin is freshly poured but if left to sit until the resin sets, the pearl toner will settle on the bottom. They look pretty bad that way. Bill Henshell and I were checking out a guitar show a while back and saw a '73 with strange glassy looking inlays. Richard said that was most likely due to lack of swirling as the resin set. Sometimes you can see the swirling technique used by the maker. Some would pull the swirling stick (toothpick?) along the sides of the triangles and then dot the center a few times. Others would turn the resin over in the center and let it flow to the edges. Some would describe circles in the center and then dot the corners. I saw some recently that were dotted from end to end. The cool thing is, no two would be exactly alike.

[jingle_jangle]

I don't know what kind of pearl toner or resin they used, but I've never had any problem with the toner settling down to the bottom of the inlay. The swirl pattern I get in my own inlays is entirely due to pouring pattern.

What I like best about the poured pearl inlays is what you mention: they look hand made! I have seen a few Ricks with redone inlays that were made from commercially-available MOP sheet material, and they look wrong; more like Charvel Surfcaster inlays, which are fine, but not Rick.

[admin]

Paul: I am always impressed with technology or technique that is an improvement over the tried and true.

Just in passing, yours inlays are first rate.

While there is a tendency for us to hold "the old days" in the highest esteem, as you have so aptly demonstrated when it comes to Rickenbackers older is not always better.

As I compare past with present, it is of great interest to see if I end up changing my longstanding world view to make it fit with new information or transform the information before me to fit my world view. Whatever is a guy to do - accommodate or assimilate? Thanks for cognitive gymnastics this morning.

[jps]

Whatever is a guy to do - accommodate or assimilate?

[rickfan60]

I don't know what RIC uses either but the stuff I use does the same thing. What do you use Paul?

[jingle_jangle]

What kind of resin and pearl toner do you use, Ted?

The toner and resins that I use are both commercial preparations that I buy in large and rather pricey quantities, but perhaps I can recommend alternatives.

For the resin, you should use any water-clear polyester surfboard coating (not laminating or casting) resin. This is slightly thixotropic, and will hold the pearl in suspension better than thinner laminating resins. It also does not yellow, whereas lam resins do not have any UV inhibitors, as they generally are engineering, not aesthetic, components. Lastly, surfboard coating resins are formulated with a soluble hard wax blended in to prevent oxygen inhibition of the surface cure. This is important to get a through-cure.

For a toner, any synthetic pearl toners made for automotive paint will work. Some polyester resin suppliers stock a paste pearl toner that does not settle out.

Now, get on that Google wagon...

[rickfan60]

The material I use works fine as long as I swirl it right before it sets.

[jingle_jangle]

Aw, c'mon, Ted...I've been very detailed and forthcoming with you...

[rickfan60]

I appreciate that. I would only ever use small quantities as I am not making my living restoring guitars.