Official Luthiers Forum!

Good point. I don't hunt either, but my friends that do spend crazy amounts of money on their weapons. I never thought about them. In my mind, hunting is all about going out and hanging out in the cold and wet. Which is partly why I've got no interest in it.

Mike

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Mike Lindstrom

Tru-oil is linseed oil based. The Tru-oil MSDS sheet mentions "modified oil" at 33%, so I sincerely doubt it is anything but partly polymerised linseed oil, certainly not a resin. Soya oil is not mentioned. Again Tru-oil is very low on solids, which is why it takes forever to build a minimal finish thickness.
I agree with Woody, Waterlox is a much better product, is tung oil based and is a true varnish.
IME it takes vastly more time to complete a finish with Tru-oil than French polishing, for a result that is not necessarily tougher.
Its solvent would be mineral spirits, but I prefer (real) turpentine for all oils or oil based varnishes. Naphtha can be used also for a faster flash time.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Laurent is on the money . Tru oil is not for guitars . French Polish is by far a better finish. It is more about an acoustic foot print to me than wearability . While FP is not as rugged a finish as lacquer or varnish it is repairable . Lindseed oil can also be hygroscopic . While at Woodstock NY I didn't see any tru oil finishes . I don't know if Laurent did or not . The finished most used seem to be Lacquer and Catalized varnish but there were a few of those that were French Polished also.
Most of the pros do seem to farm out much of the finish work .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Soya oil is not mentioned, does not mean to say that it isn't present in some form or other. According to their website it states that it is a blend of Linseed and 'other natural oils'. Which seems to suggest that it contains at least two types of oil. Nor does it behave like any other polymerised Linseed oil. As for Tung oil? Possible, perhaps probable but I can't detect the distinctive odour of pure Tung oil.

Very interesting post. Someone once told me tung oil was from the same thing as linseed, which I think is Flax seed. LInseed for some reason to me seems too sticky, a bit like a marine varnish, which is not supposed to completely dry. But I may be wrong. My friend Nathan Sweet said varnish is the best finish, but it takes too long to cure.

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"Preoccupation with an effect gives it power and enhances the error"
from "Your Owner's Manual" by Burt Hotchkiss.

Linseed is from Flax, Pure Tung oil is from. . . Tung. Not the same. Oil varnishes vary wildly in their drying times. Something like Rockhard is touch dry in a few hours (given a fair wind, but not literally).
My home made Pine Resin Varnish takes 6 to 7 hours in a UV cabinet using just one 30W visible Blacklight - that's without siccative. In full sun it's more like 3 hours, not that I would want to subject it to full sun though. Other Varnishes can take days to become touch dry. It is quite possible to oil varnish an instrument in 4 or 5 days (in terms of laying down the coats) and total time spent is not a great deal. Then comes the hardening phase followed by rubout. . . which is a bit longer.

Tung oil is from a tree , they press the nut for the oil and process that . Often tung finish may not contain any tung oil at all .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Best, not best, worthless? I don't know about all that. I used Tru-Oil on my first guitar. It wiped on easily and two coats a day dried fast and hard. That was four years ago, I think. The guitar doesn't play very well, but that's my fault. The guitar is loud and bright, which may or may not be desirable, but my point is that I don't think Tru-Oil dampened the tone any. If it did, in this instance, I would be thankful. :-) The finish seems to be holding up quite well. (See my avatar? That's the guitar.)

As to the problems in the OP, I would take the guitar out of the cold basement and see if it dries better somewhere inside the warmer house.

On a side note, I used Tru-Oil to finish an old dining room table that my wife dragged home from a thrift store. After three years and countless meals, arts & crafts projects, homework assignments, guitar building, sewing, pie making, pumpkin carving, and all-around daily abuse, I would describe the finish as plenty tough for a guitar.

The table does not sound very good strummed, however :-)

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George :-)

The things I've learned from reading through all this:
1. You need a barrier coat between Tru-Oil and oily woods
2. Tru-Oil has a shelf life and should be stored on its lid
3. Tru-Oil needs UV and/or heat to cure quickly and may need intense UV to cure to ultimate hardness
4. Only Birchwood-Casey knows the current ingredients in Tru-Oil for sure and if you say different you're cruzin' for a bruzin'
5. It's not for everyone but some use it with success
6. It cures hard enough for some people without any special procedures
7. It cures too soft for some people no matter what they do
8. You may be a slacker if you use it
9. You may be able to up-charge a customer if you use it
10 John hates it and ain't afraid to tell you about it.

Kathy Matsushita's experience with Tru-Oil on her 2010 Baritone Uke project got my attention (all expertly documented here: http://home.comcast.net/~kathymatsushita/moreprojects/htmlpages/bar1.html She acheived an excellent looking finish by curing in direct summer sun between coats on BRW back/EIRW sides/Cedar top and had no problem with it adhering. She ended up with 15 thin coats applied with a paper coffee filter, let it sit for 3 weeks and polished with Micromesh lubricated with Pariffin oil. By curing each coat in the sun she was able to get up to 5 coats per day.

For those of us without spray equipment and operating on a razor thin margin, Tru-Oil or a similar product, may offer an alternative if we can figure out how to do it correctly. Stradivarius did and look what happened!

See my previous post, there are much better alternatives. By better I mean easier, faster and more efficient application, greater abrasion and shock resistance and very importanltly, appearance. Probably cheaper too. All those can be brushed, as varnish is traditionally applied:

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

An alkyd counts as both a modified oil and a resin. I'm just sayin'...



The two are from different plants, but similar chemically. The drying component of linseed oil is alpha-linolenic acid (~50%), the drying component in tung oil is eleostearic acid (~80%). Those fatty acids are isomers (meaning they have the same molecular formula, but the atoms are arranged differently). I have no idea how that information could be useful in any practical way.

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Andrew Gamble
Sine Guitars
Custom Low-Impedance Pickups and Preamps
[url]sineguitars.webs.com[/url]

Much to the irritation of my friends and family, that's my favorite kind of information!

And thanks to everyone who has chimed in here. I learned a lot. And to the OP, the area that wasn't curing was again scraped down. More Tru-oil was applied in very thin coats and hardened well. Now I've put a couple of heavy coats in that area and it's become invisible with the rest of the back.

Hopefully I'll get the bridge glued on this weekend.

Mike

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Mike Lindstrom

while tru oil will finish wood , it isn't just about cover and shine , it is about acoustic foot print . I agree that you may use some finishes that I wouldn't use because of location .
French polish is a safe alternative to Lacquer and it has a low acoustic footprint. Finishes need to move and flex on guitars and we don't want them to take away anything tonally on a guitar. The end result is what will make the guitar look good and hopefully not affect the tone.
Sometimes you have to so what you have to do .

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I'd like to see some data on that. Any AB tests?

Me to because it sounds very much like speculation that fits just nicely with the bolony about truoil penetrating 'into' the wood. People can speculate all they like about oil and wood, but truoil is no more than an oil based varnish, you just need to climb over the top of the name and take a look into the bottle to discover that the actual amount of penetration could only be measured in microns and my belief is that when applied correctly with multiple thin coats that are each burnished to build a film, the film thickness would be no more than, or perhaps even 'less' than FP, and most certainly less than nitro.

To suggest that this could somehow have a greater impact upon an instruments acoustic transparency has absolute no foundation in fact that I am aware off.

Cheers

Kim

I can't agree with the sentiment here, in Europe many of the high end classical builders are using oil finishes, including tru-oil, on their best instruments, because of its acoustic transparency. Even Julian Bream has two Aram guitars which are tru-oil finished and I suspect that he is very picky when it comes to his guitars! Kevin uses it as he believes it is the very best acoustically for his guitars.

Oil finishes have been used on the very best guitars for centuries, including by Torres. Many of the 19th and 18th century instruments I work on have much of their oil finishes intact. I use an oil finish on my own concert instruments, some of which are being played by full time professional classical players including the Professor of guitar at The UKs top conservatoir, who uses it as his main recording and concert guitar.

I'd much sooner have a well applied oil finish than one of the over buffed products of the petrochemical industry. But that's just my own aesthetic.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Ken Parker had an archtop at ASIA last year that he finished with Tru-oil - not high gloss but I liked the look.

Gary Cornett gets a high gloss spraying Tru-oil thinned with turpentine. He hangs the instruments in the sun for several weeks before buffing.
Walter

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Walter Lay
"It's taken me so long, but now that I know
I can see. All that I do or say, is all I ever will be"
- Billy Joe Shaver

Well said, Colin.