What about Tru-oil as an alternative to shellac on acoustic instruments?

I would like to share my experience about Birchwood Casey’s Tru-Oil:

tru-oil

So far I have successfully used Tru-oil on an electric nylon “travel” guitar (a solid body instrument).  Travel guitar page.
I have also used Tru-oil on the neck of 2 of my classical guitars.

All other finishes are shellac applied the frensh-polish way.

I’m not explaining the shellac details since most will be familiar with the concept.

My reasons in favor of tru-oil:

  • Tru-oil can be applied with some simple cloth, or even paper towels in simple up and down strokes. Specific know-how or technique is not required, just don’t be sloppy and don’t use too much, and beware of the edges …
  • Application time: One coat on a complete guitar takes less than 30 minutes by doing it carefully. One coat is like the next. You may still want to do some in-between-coat light sanding to keep the surface absolutely flat for the next coats. (I prefer to be extra-careful and apply “very very little” and avoid the sanding). After about 5 – 8 coats you’re done.
  • Learning curve: Theoretical knowledge and experience required: Novice-proof! (well, it can be tricky to open the bottle once it becomes a little clogged 🙂 ) But seriously there is not much to know before getting stared (and to succeed)
  • In-between coat drying-time: 12-24 hours.
  • Final drying time: similar to shellac (10 days, better 15 to be safe…)
  • Post application: It dries the way it looks when you decide to stop applying coats. (My first shellac was “not so nice ) my second attempt was “very” beautiful and mirror-like  when I was “done”, and for the next 2 weeks, later it started to “fade” a little (became foggy) in some areas.
  • Protection properties: it becomes really hard and durable and offers excellent protection. My electic nylon travels in my suitcase (alongside other “tuff”) . minimal “micro” scratches at places, but no notable “damage” or deeper finish scratches.
  • Esthetics: natural property (like most oils) to “pop” and emphasize the natural color of the wood in a very similar way than shellac does (I did samples to compare shellac to tru-oil on various wood types including cedro, spruce, mahagony, bubinga and cypress. If there is a difference, then it is very subtle. Anyhow, none looks “better” it’ll really come down to a personal preference. (Which is more beautiful, Red or Blue?)
  • Health: not toxic (but don’t drink it!)
  • Smell: it smells a little during applications, but less than shellac (it’s actually the alcohol that smells depending on the kind you use)
  • Price: not worth-while mentioning

My reasons in favor of shellac:

  • Tru-Oil requires a perfectly sanded (I stop at 1200) and pre-pore-filled (if required by the wood) totally flat surface. (no scratch or pore-filling with pumice during the frensh-polishing process), a sloppy preparation = an ugly finish!
  • Tru-Oil does not end-up with a natural as “shiny” finish as a frensh-polish does, so you do need an additional last polishing step if you’re after a mirror finish. (something that is not required after a proper frensh polishing job)
  • I have not yet tried to repair a true-oil finish. I suppose however that fixing will be tricky and that you probably need to sand it all off and start from scratch. (it doesn’t have the dilution / melting properties that shellac has which allows for “easy” repairs.)
  • Inflammable: (careful on disposing used towels, like all oils they heat-up while drying.)

What I don’t know: (and where “your” experience would be very welcome):

  • Tonal properties: Since the application remains micro-thin (if reasonably applied), and since it is not “absorbed” into the wood (hence doesn’t transform or alter the vibrational or stiffness properties of the wood itself), I don’t believe it would harm the sound (vibration) properties but this is only an assumption…. Any experience?
  • How does it age? My first application dates back to 2013, (the travel guitar) and so far I can’t see any change, but 2 years is too short to tell. A solid body like my travel guitar doesn’t vibrate as much as the box of an acoustic guitar….
  • Is it likely to “crack” under permanent vibrational influence (or string-tension changes) like would be the case on an acousitc guitar top? Unlikely maybe, but … I don’t know.
  • Can you “tint” it? I guess, since you can tint any oil, but since I haven’t tried, I don’t know.
  • Some say they have successfully managed to spray it on…. ( but since I have not tried, I don’t know)

Conclusion:

  • As long as I don’t have more information or feed-back regarding the “tonal properties” or the “aging” aspects, I prefer to stick with shellac. I’m also not in a hurry, and my shellac application expertise needs a lot more practice and experience! 🙂

Okidoki, enough details for now. Hope some find this useful, and any feedback very welcome!

Cheers, Marc

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