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Howdy guys,

I'm finishing my latest with Tru-oil and I'm having a frustration. There's one spot on the back that the tru-oil is staying gummy. I assume it's related to some careless fool getting CA accelerator on the finish in that spot. I've scraped back to wood, but it still doesn't want to set up there. Wash coat of shellac underneath and pore filled with CA.

Any suggestions?

Mike

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Mike Lindstrom

maybe you should have built a gun instead.

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

Had the same problem on my last one. For some reason, one side of the headstock plate (EIR) had streaks where the Tru-oil stayed tacky. CA wasn't the problem for me. Never had any near the headstock. It had to be something to do with the wood. I ended up just applying multiple heavy coats, waiting a couple of days in between each coat, and it eventually hardened. Maybe someone with more Tru-oil experience can educate both of us. The finish went on fine everywhere else it seemed. Strange. Be patient and good luck.

Aaron

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Aaron Craig

It's a gift for my nephew. I don't think dad would approve. Though I could get some cool new tools...

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Mike Lindstrom

That is a known problem with certain woods,read rosewoods,when using oil finishes.Sealer coats usually prevent this from showing up.
Tom

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A person who has never made a mistake has never made anything!!!

I knew oily woods were a problem with polys, but I didn't know it was truoil too. Either way, I'm going over padouk and purpleheart.

Mike

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Mike Lindstrom

I've tried Truoil over Ind.Rosewood and it dried. Just took much longer compared to using it non oily woods.
My bottle of Truoil is years old and is now unusable (don't forget to store the bottle on it's head).
I have noticed that the crud that forms around the screwcap is HARD. Surely that has to be a resin.

The resins in rosewood can interfere with the curing of some finishes. I learned this years ago when using a brushed oil varnish finish. Some of my coats took a week to cure.

A seal coat of shellac would be the cure.

I stopped using tru-oil for that reason. Never was able to get it to harden on certain woods, never had a problem with padauk.
I've never had a problem with Minwax wipe-on poly on any wood.

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Old growth, shmold growth!

I am so against this stuff for guitars. The final stages of guitar construction are the hardest , Fit and finish , is what makes the guitar look good. I agree not all good looking guitars are good sounding , as is not all ugly guitars sound bad . As a builder you need to come to the understanding that A I can finish a guitar, or B I can't finish a guitar.
While I can finish , with all the restrictions and hazards I send them out for finish . I can tell you that if you think you can finish a guitar in 2 days , you really are not finishing . I spend that much time just to get the fill and color right . In reality I may spend more time on the finish that the build .
The finishes out there are so much better for the beginner . Avoid anything from Home Depot or Lowes . This isn't luthier grade. Of all the deft finished guitars I made in my early days , all are checked to high heaven . Not till I starting using real finishes did I get a true marketable finish.
Will tru oil have a following ? Sure but I don't think I ever seen a pro use it .

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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

Im with John on that
After a couple of guitars
They look OK ish for a while but the stuff has little resistance to wear and tear or even fingernail scuffs. My Classical looks 5 years old and its never seen a pick or been out of the house.
Never again

I have to disagree. Truoil is nothing but an oil varnish. It's just a thin one. I also suspect it DOES contain a resin - the clue may well be in the 'modified oil' statement, which may well suggest that it is an Alkyd. I'm guessing, but Truoil does not behave like any drying oil that I've come across, highly polymerised or not.
I also don't know where you get the 2 day statement from. Sure you can finish it in two days, if you like that type of finish. For those who prefer a higher gloss, it will take more like 2 weeks and more.
I tire of people making statements such as 'you can't do X, Y or Z.' I've heard it in the classical world for years. Many of them haven't got a clue because they've tried nothing else but 'French Polishing'.
The truth is that there are many different types of finishes. Each has it's advantages and disadvantages. Pretty much all of them will look professional if executed right, including Truoil. Not everyone likes the sheet of glass on wood look, many clearly do. Take your pick.

Kind of the same statement that I've heard regarding French Polish - and I've heard it often. Sometimes 6 months after the instrument was handed over.

FWIW, Jonathan Kinkead offers Tru-oil finishes as an upgrade option. To each his own, I guess.

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George :-)

Is this a hide glue thread yet?

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No resin in Tru-oil, apparently they use a proprietary polymerised linseed oil. But I agree, it acts like a varnish, and not an oil like pure tung or linseed oil. However it is soft, much too soft for a good and durable guitar finish IMHO. Besides the fact that it is poor in solids content and takes forever to build a decent finish.
Sealing with shellac definitely works, but kind of defeats the purpose of using an oil varnish: the appearance and depth of the wood is not the same. When I seal with shellac I wipe on and off with linseed oil, then spray the shellac seal coat.
The solution to Tru-oil not curing on oily woods is to thin it further and apply it very sparingly, it may require a couple of light coats like this to really seal the wood. It would be true of any oil varnish BTW, and may take over a week to fully cure for the first coat. It happened to me with Waterlox on cocobolo, but eventually it cured. I had to wipe it with naphtha a couple of times, and re-seal it.
There are many excellent oil varnishes perfectly suitable for acoustic guitars without using lesser products:
- Behlen Rockhard
- Behlen water white restoration varnish
- Ace hardware interior varnish
- Pratt&Lambert #38
- and my favourite, Epifanes clear varnish
I've used them all very successfully on steel string guitars, except the P&L #38 that Velasquez uses.

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

I recently used tru-oil on cocobolo with no problems...

Actually Laurent the MSDS for Truoil states 11% (by weight) Proprietry Linseed oil, 33% 'modified oil' Proprietry. According to the Maestronet archives Oded Kishony (Violin maker) was told by a Birchwood Rep that the 'modified oil' was Soya. In itself Soya is classed as a semi drying oil. Soya can be converted into an Alkyd resin, although I'm not stating that Birchwood is actually doing so.

I used Tru-oil on my first one built with Al Carruth. To prevent stickiness and to make the finish cure he had me put a few drops of (I think) japan drier into the oil. Then he let me borrow a blue lightbulb, either blacklight or maybe it was infrared but I can't remember for sure, to shine on the finish which also helped it cure. On subsequent coats, if I had an area not drying as hard as the rest, I hit it with the light for a few hours and it cured.

If he sees this he can confirm I have the japan drier and type of light right.

Thanks for everyone's thoughts. This guitar is for my 7 year old nephew, and I figured if tru-oil stood up to whatever abuses hunters' gun stocks are subjected to, it would be good for him. I like to french polish (thanks Robbie O. and Michael Payne for your excellent classes), but I don't have the time for that between now and Christmas. Plus, I was hoping the tru-oil would be a little tougher than my shellac. Maybe it'll be a terrible idea, but it's a first guitar for a 2nd grader...

So some other thoughts:

2 days? I'm on day 8 with the tru-oil. 2 a day thin coats and wipe them down before it sets up. The truoil takes less of my time, but to get an actual finish, it still takes a chunk of the calendar.

Resin? One of my finishing books (maybe Flexner?) says that Tru-oil is a combination of varnish resins and polymerized oil. I don't know if that's true, but at least someone thinks so. I am certainly building a glossy finish, which makes me think there must be something in there.

It's pretty chilly in the basement these days. Maybe I need to wait longer than normal for it to cure.

And some questions:
Laurent - When you thin the Truoil, what do you use?
John - What finishes do you recommend?
Anyone - If those who say it isn't tough are right, why do hunters like it? Or maybe they don't?

Thanks again,
Mike

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Mike Lindstrom

If Tru-Oil is mostly what they call "modified soya oil", then I would be surprised to find that it is not at least in part an alkyd: soya is the most common thing used to make alkyds. If it dries hard and non-rubbery, I seriously doubt it's without resin.

Apparently, what causes oil finishes to not dry on some woods is antioxidants in the wood. Makes sense, since oils cure by oxidation. If this is happening on a sealed and filled back, then I don't know what's going on, unless you sanded down to the wood, or antioxidants found their way into the finish some other way.

There's four ways I know of to get oil finishes to dry faster: more oxygen, more heat, more UV light (as in a blacklight or a nearby star), or a catalyst (usually heavy metals in some form, Japan drier would be an example). So if it's in the basement, in the cold, then it is getting neither UV nor heat. That could be a piece of the problem. Try pointing a black light on the sticky spot for a day or two, see if it cures.

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

Truoil was (I've been told) designed for Walnut gun stocks. I seriously doubt any gun companies are using it. (but companies don't always use the best product)
I recently stripped the tru oil off a home made gun stock and re finished it with catalyzed urethane for a local hunter. He finished it with truoil a couple years ago and wasn't happy with the durability.

Truoil is polymerized tung oil..........or in other words, it's tung oil that's been cooked. The cooking causes it to partially cross link. This makes it cure faster, and also makes it a little harder. I seriously doubt there's any resin in it. I suspect, along with rosewood type oils, being too thick would impair curing.

I've experimented with truoil, but haven't and wouldn't put it on a guitar. IMHO Waterlox (a true wiping varnish) would be alot better finish, and could be applied the same way people apply truoil. That's doesn't mean I think it would be a good finish for a guitar though.

Fire away at me for not liking truoil. It's no more durable than French Polish. Most of the guitar buying public want the glass look. I suppose with a good pore fill, and enough coats this could be accomplished with truoil. IME there's other finishes that are more durable, more acoustically transparent, and even easier to apply with basic equipment and skills.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

I don't hunt myself but I know a lot of hunters. The ones who'd care about their gunstock's finish are the ones who baby their guns the most. Many treat their guns way better than musicians treat their instruments.

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http://www.birkonium.com CNC Products for Luthiers
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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/