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Question and research claims of "penetrating" oils and resins!

Discussion in 'Luthier's Corner' started by akori, Nov 3, 2013.

  1. akori


    Oct 18, 2007
    Just to share the info. from the research I've been doing for months on the "penetrating" properties of *all* manner of oils and resins, from tung oil to epoxy and CA glue. The idea here is obviously about improving the hardness and reflective tonal properties of fretless fingerboards, producing liveliness, and/ or compensating for relative dead spots (not those caused by the bolt-on phenomenon).
    I've been building many fretlesses , all of the Fender Jazz/ P-J type, with many body woods, fingerboards and neck woods. I've been learning a lot, and the more I trust my ears, and use empiricism along with research , the clearer the complicated picture is becoming. The builds sound incredible, but I want to seek perfection on every one. Duh.

    But the main point here, is, I looked for weeks on the internet, for VALID scientific research on the "penetrating " qualities of al the agents we'd use to make, say, an Indian rosewood board more reflecive, allowing a great growl. (Not that I'm a huge fan of ebony boards on maple, because they can be so bright and have relatively scooped mids). I greatly prefer the sound of Brazilian Rosewood, and similar woods, for a well-balanced, musical interaction with strings re; growl, warmth, fast attack, etc., be those strings great flats (TI JAZZ!) or rounds (TI JAZZ ROUNDS!).
    OK, here's the scoop; I found ZERO reliable, well-researched proof that ANY oil, or resin/ acrylic/ polyester/ etc., actually penetrates *any* wood. (OK, maybe balsa...) Some might say who cares? Well, to really harden a wood, and blend the hardness deep in, without a thick resin surface on top, would be very nice; Something closer to wood on top, with the density and speed of vibration beneath, creating a more natural, musical tone. Or, to avoid the gummy effect of too much linseed oil.
    (NOTE: I have not been able to find good reliable info on specialty products like hardened wood...can't tell if they're malarkey or not, though I feel the idea is the ideal).
    Just with lets say oils; Here's a link on heated vs unheated linseed oil. The extra step is useless. http://www.woodworkersresource.com/content/should_you_heat_your_linseed_oil_before_applying_it/
    Better yet (sorry I can't find the bookmark, is a long article with many top notch luthiers describing the almost non-existant penetrative quality of all the oils we use. You can find it. I've got a cold & am beat tired...This one will really make you skeptical. These guys are not yahoos. I recall names like Sadowsky, Lull, Suhr, etc., in the article; definitely not ******** talk over a beer kind of crap...

    Lastly, I looked all over in the resins industries for science-based articles proving the effectiveness of pulling epoxies, polyesters, etc., into wood. What I found, time and again, is that the only thing that "penetrates", is the penetrating agent. The resin stays on top! Some boat forums have people in vicious arguments about this, but there's no science to prove any real penetration. All I find singing the praises of "penetrating" resins comes from (surprise!), the *manufacturers* and *sellers* of said products. Enough said about that. The Only thing that I had ANY faith in , was a cement finisher in Los Angeles who just seemed a credible guy. He said that he wouldn't do designer painted cement floors without the use of penetrating agents added to epoxies, because of the huge cost of going back to repair his jobs, and that the added cost (passed on to the client), was worth it. But that's cement, and he could still be wrong.
    Final statement; don't just buy the idea that ANY oil, or resin, either with the use of some penetrating vehicle or not, is going to drive your hardening agent deep into the wood. The MOST I've seen from big luthiers, smart guys running empirical tests, and even-laughingly so- from marketers of said products, is in the 1-3 mm range. Rather pathetic results.
    If anyone can point to some GOOD science on this that defies what I've found, I'd love to see it. Frankly, I'd LOVE to be able to drive a hardening agent into , say, Indian rosewood, without a thick coat on top. Again, I think the *concept * of hardened woods, such as we've seen here on TB, is great. The process wherein the resins are supposedly driven into the wood under intense pressure in an autoclave? Sign me up if it works.
  2. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    Larry Davis from Gallery Hardwoods has his "acrylize" process. This gets his resin very deep within the wood.

    As best I can recall: He did a full body as a test subject and when it was cut, it had gotten nearly all the way through to center. That is to say, around 3/4" depth of penetration, if I remember the photo correctly.

    However, this is no ordinary process; he uses a pressure chamber, proprietary resins, and a proprietary process involving pressure and/or vacuum, and I believe he may once have mentioned temperature on this site.

    So while it may not be like any of the processes you mention, it may be the end product you're looking for.
  3. akori


    Oct 18, 2007
    Yeah, PilotJones, this "acrylizing" process-if effective, seems like it should be pursued. With the justifiable interest in finding the most stable (and sustainable) woods, not to mention the cosmetic possibilities of including woods that may look fantastic but otherwise not be stable enough for a fingerboard or a neck, I have hopes that it will become a regular facet of making fine guitars.
    I have read a bit on the process, and I want to see the proof myself. Thanks for the info . Pure synthetics (Graphite)hold great promise, but have largely failed to deliver, being surprisingly weak and heavy, often compromised in their very design. Acrylizing wood, if it works, is VERY intriguing. I gotta' pull the trigger and go for a good test...like some crazy figured birdseye neck/ fingerboard fretless, acrylized to the core...see if it A); is stable as hell, and B); still sounds like maple! I've seen some *BEAUTIFUL* pics of acrylized birdseye here on TB.
    Thanks again-
  4. Hi.

    Why not try it then?

    Does involve a bit (ok, a LOT ;)) of DIY spirit, but appropriate pressure vessels can be found on scrap-yards. Used autoclaves for scrap piece testing purposes aren't very expensive either, but to be able to effectively and with repeatable results "harden" a FB for example, the dimensions needed can make it difficult to find an affordable commercial product.

    With heat cured infusion epoxies it shouldn't be too hard to pressure treat a thin piece of any non-metal matrix thoroughly.

    Good luck.

  5. akori


    Oct 18, 2007
    T Bird: i dig your DIY approach. That's the way. But i also agreee I've rarely, if ever seen an autoclave large enough to house even a bass fretboard blank...I ought to see what second hand stuff is out there...
  6. "Wildwood" and "Diamond Wood" are other products completely impregnated with resin (and dye), so it is absolutely possible, but those are also done with pressure.

    I have cut wood that has had penetrating oils applied, and it certainly does penetrate, but the penetration varies tremendously with the thickness of the product, the wood, and the grain. You can see that it has gone a 1/4" into some end grain but not be able to really see if there's any penetration at all on side grain of some hardwoods. It's all over the map.
  7. akori


    Oct 18, 2007
    Hey Major Softie: 1/4 inch penetration with an oil is impressive! Though you did mention it's highly variable. We'd have to choose a blank of ebony, for example, apply and section every inch for a foot or so...One day I will try.
    Question...which oil provided that 1/4 " penetration (even in a small spot, and which wood was it)? I'm VERY interested in those details. Maybe one oil can be proven to be superior, and tweaked for optimal performance.

    As to Dymondwood, I had forgotten about them...Just went to their site. I think it's another very promising direction for hard, stable, musical fingerboards. But cripes did you see the specific gravity of their product? Wow; birch at 1.18 to 1.30. African Blackwood (which is a tonal beast and maybe the heaviest in use) is about .90 as I recall... Anyway, a great option. I confess, though I LOVE wood, and I'm developing an acute awareness of tap - tone recognition with reliable results, I dream of fully synthetic products that sound great and stay put. At least as far as necks / fingerboards go.

  8. Sorry, Akori, I do not remember which oil that might have been, but it was, as I said, on end-grain, and it was probably softwood.

    If forced to guess, then from the stuff I usually have around, it would most likely have been either some tung of unknown manufacture (I've had lots of different ones) or one of the older high V.O.C. Danish Oils. Those older Danish Oils were quite thin.

    This would be really easy to test on a piece of white wood. With the Danish Oils they even had stain in them so it was very clear exactly how far they had or had not penetrated. They could also be thinned and you would be able to determine if that resulted in more penetration.
  9. It's not a fretless but the ebanol fretboard on my old aluminum neck Kramer has held up very very well.
    On oils penetrating,I've had good luck with both tung and linseed oils mixing them about half and half with mineral spirits for the 1st coat to get them to penetrate into the wood more.I don't know if that would make much difference with something like ebony or rosewood but it helped with Jatoba which is also a very hard wood.
  10. Penetrating hardeners for concrete work as a chemical reaction for the most part. There are a few that seep into the entrapped air in concrete, but they often don't go all that deep.

  11. akori


    Oct 18, 2007
    Yeah, Jamlowsound: it would appear there's no easy magic about penetration here. Not yet, anyway. I think concrete may be more practically permeable than wood, at that!
  12. Typically concrete has an entrapped air content of 4-8%, depending on use and if it is inside or outside. This is controlled with various admixtures. Some uses require a 0% entrapped air content, which is accomplished with a densifier and then usually has a penetrating coating applied to it to seal the surface. The entrapped air is what makes concrete somewhat permeable.

    Neat fact, if it wasn't for the entrapped air, concrete wouldn't stain when you spill something on it.


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