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Hobo
09-25-2011, 12:33 PM
Hello,
This is my first question in this Forum. Actually not a vs. question, but rather a compatibility issue: I really like Tru-oil for its ease-of-use and soft sheen you can achieve. I've used it on a number of banjo's I've built and have been pleased with the results. Lately, I've been interested in trying my hand at French Polishing a Ukulele. I am wondering if it's possible to French Polish overtop of a thin base coat of Tru-oil to speed the French Polishing process up a bit. I'm not interested in spraying or complicated technique's at this point. Any and all opinions, most welcome.
Thanks, Joe

Rick Turner
09-25-2011, 12:43 PM
Yes it is, but you might want to try an alternative: doing a couple of coats of epoxy and then French polishing over that.

Michael N.
09-25-2011, 12:54 PM
I don't really see how it will speed it up. The first few applications of French Polish can go on within an hour (or less) of each other. It's only when the film builds that you have to let it harden longer. You are also risking problems with Shellac over Tru-oil. I'm fairly certain that it will stick to it but there is always the possibility that it will craze.
You can always brush (or spray?) the first few coats of Shellac on. It does take a bit of practice to get an even film. You can always use the pad on top of those brushed coats. Even though I've done countless hours of French Polishing I no longer bother. I just brush on Spirit Varnish. Takes but a fraction of the time once you have mastered the brush.

Hobo
09-25-2011, 02:50 PM
Thanks for the comments!! I guess my reason for doing a French Polish is just to do one and get it out of my system. I might hate it, but for the moment I'm intrigued by this very old-style, traditional method. I was also wondering about the merits of using pumice and solvent to fill the grain or skip that and go for a filler like Timbermate. I've notice a trend towards non-filling open grain wood. As you can tell, I'm a novice at finishing. The wood type I'm using is mahogany.

Tarhead
09-25-2011, 05:07 PM
Try a coat of Sealcoat Spray Shellac http://www.homedepot.com/h_d1/N-5yc1v/R-100176744/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 first, followed by a very small amount of talc applied with a damp (with Denatured Alcohol) applicator. I use a ~1" square of an old white wool sweater wrapped in a piece of cotton T-Shirt. Slowly add 1lb cut shellac to the applicator as it starts to pull.

erich@muttcrew.net
09-25-2011, 09:28 PM
As Michael said, yes you can - keeping in mind that there could be glazing issues depending on just how well cured the tru-oil body is before you go ahead with the french polish.

Our method is actually the other way round: FP first and then TO on top of that. We've found it is really easy to touch up the TO finish - though I'm sure with the right technique you can also do a quick rub down of scratches or glitches in FP.

As to grain filling with pumice, it really depends on the wood - at least it has for us. So we always do a test on some scrap wood first. For example, I don't like the look you get with pumice-filled rosewood unless you add some ebony dust to the mix. The fine rosewood dust is lighter than the wood color, so you get lighter colored streaks in what was formerly the deeper (and therefore darker) pores. By adding a little ebony dust, you can keep the filled pores a darker color, which I think looks better. But of course YMMV.

EDIT: With other woods, including maple, cherry, mahogany (sometimes) and vaious others, we've had excellent results with shellac sealing and pumice filling.


SECOND EDIT: You can also use TO to do the pore filling. There are two methods I know of:

One is to use a sanding pad or linen while applying the tru-oil. The abrasion develops a slurry that pushes in and fills the pores, much like the shellac/pumice method. Let dry well, sand down afterwards, repeat until done.

The other method is to push the tru-oil into the pores with your finger, let dry, sand down, push more TO in, let dry, sand down.... Take your time and repeat over and over until you get a really smooth, glassy surface when you apply a coat of TO. I like this method better than the other, but have found that some very slight imperfections can show up months later as the varnish continues curing and sinking down deeper into the pores.

One way or the other, TO is not a finish I'd recommend to anyone who's in a hurry.

Michael N.
09-25-2011, 10:49 PM
Open pored glossy finish looks a little odd to my eye. As though the wood has suffered some sort of contagious disease. Maybe it's what one is accustomed to but I think it looks much better with a dull or matte finish.
I've only tried the more traditional forms of grain filling: Pumice method, Silex filler, Oil sand method and egg white/wood dust. They all work. They all sink over time. Be prepared to do several applications over a period of 2 or 3 weeks. That will minimise the sink back.
Even though I essentially use Shellac, I believe that an Oil finish straight onto wood shows the grain at it's best. It's a pretty easy test to do - one half of an off cut with Oil, the other French Polished. The only reason I use brushed on Spirit is for pragmatic reasons.
I used to spend some 20 hours+ on French Polishing a Guitar. I thought that excessive, considering the number of hours involved in the woodwork. Some folk claim to do well over 40 hours! It's a form of madness.

erich@muttcrew.net
09-26-2011, 03:00 AM
Good points, Michael.

If you don't like the glossy finish you get with tru-oil you can (carefully) buff it down to a satin or matt finish with extra fine sanding pads. A lot of people use fine (000 or 0000) steel wool for this, but I find you get a much smoother, finer grained finish using aluminum oxide pads.

Hobo
09-26-2011, 12:43 PM
Certainly a lot to think about. Thank you all for the advice and council... one and all!

Strummin simon
09-27-2011, 03:22 AM
how i finish with tru -oil is to apply the first coat, rubbing the TO in with fine wire wool.

leave a day, gently sand, recoat with the wire wool method, leave a day

then when dry gently rub over with fine wire wool until smooth to the touch.

then coat with TO using a cloth, leaving to dry for 24 hours inbetween coats. i find 4-5 coats is fine.

joejeweler
09-27-2011, 06:42 AM
how i finish with tru -oil is to apply the first coat, rubbing the TO in with fine wire wool.

leave a day, gently sand, recoat with the wire wool method, leave a day

then when dry gently rub over with fine wire wool until smooth to the touch.

then coat with TO using a cloth, leaving to dry for 24 hours inbetween coats. i find 4-5 coats is fine.

Just wondering if you get small pieces of the steel wool imbedded in the TO finish when applying it that way?

I've always used my finger to rub multiple fine coats of TO in over several days. Using steel wool and/or fine sandpaper between coats i sometimes notice a bit of steel wool getting trapped in the finish, but can usually get it out.

I like TO for it's ease and safety,....no fumes to worry about and use it on a lot of things,.....mostly gun stocks though and some bridge touch ups or when i've made a new bridge. Never heard of applying it with steel wool though.....

strumsilly
09-27-2011, 07:54 AM
NOT MEANING TO HIJACK THE THREAD, BUT HOW DOES THE TRU-OIL DIFFER FROM TUNG OIL. is the result superior?

Michael N.
09-27-2011, 08:40 AM
That depends what you mean by Tung oil.
Pure Tung oil is more like finishing with a thin version of linseed Oil because that's all it contains - tung oil. It doesn't build very well and offers very little in the way of protection. Tru oil acts similar to a thin Varnish. After multiple coats you can buff it to a pretty high gloss, although I wouldn't call it a hard surface finish.
Just to confuse matters some 'Tung oil' is a mixture of drying oils and modern Resins, very similar to Danish Oil. It sort of ends up somewhere between Pure Tung Oil and Tru-Oil.
It's all very confusing but it's the way that manufacturers market their product.
Personally I would stay away from the Pure Tung Oil. Danish Oil and similar products are fine if you are very careful with the instrument. The good news is that if the wood starts to look a little grubby it is very simple to apply more Danish oil.
Tru Oil tends to be the thicker of these finishes, builds faster and will get you to gloss. It won't offer that much more protection than Danish Oil, the gloss can be very deceptive in this case. Matte or Gloss, any finish that is largely made up of a drying oil does wonders for the aesthetics of wood.

thistle3585
09-27-2011, 08:53 AM
I don't mean to split hairs but french polishing is a technique and not a type of finish although most french polishing is done using shellac based finishes. Tru-oil is a brand name of a linseed oil based finish. Here is a great description of using it. http://www.lmii.com/carttwo/truoil.htm

Pete Howlett
09-27-2011, 09:31 AM
This has been a subject of discussion many times. William King's method is probably the easiest and most simply explained. It is in the archives of this forum - just do a search.

Strummin simon
10-03-2011, 03:33 AM
i ve never had problem with bits of wire wool left on the wood.
i apply the TO with the wire to help fill in any pores.

then inbetween coats rubbing with wire wool to get a smooth to the touch finish.

this is just my opinion on how to do it, it works for me after trying several different ideas.

i'd look at william kings method if i could be arsed to search for it!

Pete Howlett
10-03-2011, 05:34 AM
You ought to be arsed! You might learn something :)

erich@muttcrew.net
10-03-2011, 06:02 AM
...i'd look at william kings method if i could be arsed to search for it!

Never mind, it wouldn't have been of any use.

W.K uses Watco Danish Oil, not Tru-Oil (and actually makes no mention at all of Tru-Oil anywhere on his site, at least as far as I have been able to determine using google's advanced search and every imaginable (mis)spelling of Tru-Oil). The method he describes is not applicable to Tru-Oil - at least not directly.

And BTW, Tru-Oil has been used in gunstock finishing for years and there are plenty of sources out there describing various methods of use with regard to pore filling, application, sanding, thinning, finishing, etc. etc.

Rick Turner
10-03-2011, 06:11 AM
"Waterlox" is a really nice "tung oil finish" that is technically a "long oil varnish" since it is a blend of tung oil with alkyd and phenolic resins. It may provide better moisture protection than Watco or TruOil, and it goes on beautifully over epoxy pore fill/sealer for a hybrid finish.

erich@muttcrew.net
10-03-2011, 06:37 AM
I don't mean to split hairs but.... Tru-oil is a brand name of a linseed oil based finish....

Me neither, Andrew, but linseed oil (polymerized) only makes up about 11 percent in the tru-oil mix, so I don't think I would really call it "linseed oil based".

Michael N.
10-03-2011, 07:11 AM
That depends. . . on what the 'modified oil' bit means. That might be Linseed as well.

Rick Turner
10-03-2011, 07:54 AM
The typical modifications to drying oils are processes that either partially oxidize them (like "sun thickened" or "boiled" linseed oil) or add driers like cobalt (aka "Japan Drier") that are catalysts to the oxidizing process.

The definitions for different finishes have become all screwed up with terms like "oil finish", "varnish", "lacquer", and even "urethane" now overlapping tremendously. Most of the hardware store finishes sold as "oil" are actually varnishes formulated to be wiped on by the home handyperson. A number of the "new wave" of hand craft furniture makers who came up through the 1950s through '70s formulated their own wipe on "oil" finishes by combining spar varnish, linseed oil, and mineral spirits. Sam Maloof, Art Carpenter, James Krenov and so on really kind of pioneered these easy to apply finishes.

Also, I'd like to point out that some folks object to "plastic finishes" like polyurethane and polyester while promoting nitrocellulose lacquer as being a traditional finish...but nitro lacquer is, in my definition, is a plastic finish. It's a thin coat of celluloid, arguably plastic. And traditional? What's the cutoff year for that? In not too many more years, polyester will become defined as a traditional finish...it's only about 60 years behind nitro lacquer on guitars...

erich@muttcrew.net
10-03-2011, 09:23 AM
That depends. . . on what the 'modified oil' bit means. That might be Linseed as well.

Might be, yes, but we don't know. So can we simply assume it is modified linseed oil and call it "linseed oil based"? Not really.

Rick Turner
10-03-2011, 10:17 AM
One of the problems, of course, is that the finish companies are very circumspect with regard to ingredients, and so what they call the stuff and what it is are two different things.

Two ways to find out more: MSDS ... Material Safety Data Sheets...which every supplier must, by law, provide if asked. You won't get the formula or process by which the stuff is made, but you will get the ingredients. The other is to find a "poison control" data base. They have ingredients listed, too, as it's absolutely necessary to know in order to properly treat poisoning cases.

Sven
10-03-2011, 11:41 AM
Yeah well... don't know what it consists of, but I like the methods (and results) described here:

http://www.thegearpage.net/board/showthread.php?t=711780

It's a thread from another forum, some of the builders have achieved pretty darn good results with Tru-oil.

I think Tru-oil is good. Since I don't have a spray booth. But I would love to be able to do more professional finishes.

Michael N.
10-03-2011, 12:39 PM
Might be, yes, but we don't know. So can we simply assume it is modified linseed oil and call it "linseed oil based"? Not really.

Hence the word 'might' in my reply. So by logic we can't say it isn't Linseed Oil based either.
I looked at the Casey MSDS for Tru Oil a few years ago, partly because I wanted to know how a polymerised Oil acted more like a resin Oil Varnish.
For all I know the 'modified oil' might be a resin - technically I understand that to be a possibility. Over the years there have been a lot of guesses, from super heat treated Linseed Oil to Soya oil. All I do know is that it doesn't act like the heat treated Linseed Oil that I made.
As for method. There's not much to it. You'll have a harder time filling Pores than applying and polishing Tru oil, providing you have patience. The big advantage is it's simplicity and the Oil on wood effect but like all (I guess) finishes, it has it's disadvantages.

BlackBearUkes
10-03-2011, 03:38 PM
"Also, I'd like to point out that some folks object to "plastic finishes" like polyurethane and polyester while promoting nitrocellulose lacquer as being a traditional finish...but nitro lacquer is, in my definition, is a plastic finish. It's a thin coat of celluloid, arguably plastic. And traditional? What's the cutoff year for that? In not too many more years, polyester will become defined as a traditional finish...it's only about 60 years behind nitro lacquer on guitars..."

Call nitro lacquer whatever you wish, but the main difference to me is if a finish can be repaired without stripping the instrument or using super glue for the repair. Nitro can be softened and repaired with the same nitro, or shellac, or any number of other products. If done properly the results can be outstanding and last as long as the original finish. Old nitro finishes can be renewed and if done right can be very good looking without losing the vintage look.

The newer poly finishes are extremely difficult to do anything with once they have cured. I see mostly poly finishes on all the newer guitars and ukes. If they make it into my shop for repair due to damage, cracks, drops, etc., I will repair the structural damage but can't and won't repair the finish. I usually refer the customer back to the maker for finish repairs.

Pete Howlett
10-03-2011, 05:12 PM
I don't like the poly finishes - too difficult for mortals to repair... TruOil is a great finish if you can't get to spraying. It's easy to understand and use and tho 'amateur' to the point of being crude in its application, provides a very professional finish. Not mentioned a lot is 'varnish'. I met Ohio luthier Roger Thurman back in 1998. Apart from his ground breaking work on porting he showed me a guitar which had been sprayed with violin varnish. It looked as good as cellulose and I understand there is quite a bit of technique that goes into this but it is another one of those 'mysteries' only a few are privvy to...

jcalkin
10-03-2011, 05:37 PM
Much of this argument has been spurred by the collector's market, ie: preserve instruments at all costs. I think that's a shame. Battle scars are honorable. Stupid scars can be dealt with using a bit of humility. It's ironic that while we do our best to preserve the "perfection" of new instruments, companies are making money turning out pre-damaged relic instruments. I wish I played enough to honestly wear out an instrument, any instrument. They could burn it with my corpse.
Gunsmiths have been dealing with Tru-Oil for a lot longer than most luthiers. A few have converted rotisseries into racks that slowly spin a sprayed TO gunstock to keep the thick film from sagging. It's all been documented if you care to spend the money on books. TO is miles ahead of the thick tone-killing poly found on cheap instruments. But there are also polys that can be applied by hand, go on very thin, and look pretty good (at least in their satin versions). They don't look like a fine nitro finish, or even close, but they protect the instrument, don't effect tone, and can be touched up. If you want high gloss you have to do the work, even with Tru-Oil. It's not so much a matter of being lazy or not, as what makes you content.
I'm feeling old these days and not all that pretty. I don't care if my personal instruments look the same way. If I need to sell instruments I have other decisions to make. Just like everyone else. But I blame the collectibles market for the need to keep instruments pristine. It shouldn't be a matter that most of us should have to worry about. It shouldn't even cross our minds.

Moore Bettah Ukuleles
10-03-2011, 05:49 PM
I'm feeling old these days and not all that pretty. I don't care if my personal instruments look the same way.

Priceless! We've missed you John. ;)

Rick Turner
10-03-2011, 06:47 PM
I'll tell you where the rubber meets the road...

Your instruments hanging in music stores.

How do they look after three months?

If they're done in "oil" finishes, they look like sh-t if they've been handled at all.

And I'm one of the guys who pioneered oil finishes with my work with Alembic in the early 1970s. Traditional "oil" finishes are just not competitive in that manner of presentation. Sorry...

Waterlox or TruOil over epoxy might be competitive...but if you're trying to build up from scratch with a drying oil, you don't have a chance in the retail environment.

Pete Howlett
10-04-2011, 02:00 AM
And that is why I recommend it as an 'amateur's' finish. I rarely, unless it is requested provide it as a finish. No self respecting builder would...

Strummin simon
10-04-2011, 03:40 AM
You ought to be arsed! You might learn something :)

quite right Pete. i do intend to. i was just being a bit flippant

my way of finishing is down to my experimenting. it is an amauter finish. i'll check out the suggested method

jcalkin
10-04-2011, 05:20 PM
Rick, I remember when Alembics hit the magazines. I didn't catch up until the '70s. No one was sure what you were trying to do, and I wasn't sure if I liked the dull finish or not. It takes a while to adjust to new things. Besides, they were basses, and I didn't care about basses.
But Tru-Oil behaves like a varnish. It forms a hard coat, takes a shine, and greasy finger prints can be wiped off as easily as on lacquer. Hunters have taken Tru-Oiled rifles all over the world, beat the crap out of them, and had them nicely restored when they got home. It's good stuff.
It's not a pro finish because it's too slow, not because it doesn't look good. It's still a good amateur finish, which is what Hobo was talking about when he began this thread. He might be ready to move on from it, but it's still good stuff.
Collings, for one, gets a big up-charge for spraying Bar Top varnish on the top of their instruments. I've used both Bar Top (McClosky's) and Tru-Oil, and I'd rather have Tru-Oil on my expensive instrument. It's at least one step closer to the varnish people think they are getting, even if the chemical mixture is way different.

southcoastukes
10-04-2011, 06:15 PM
I've tried just about every finish mentioned in this thread. They have their good and bad points.

What truly astounds me is that there is almost no concern over the sound properties of these coatings.

Rick, as always, is wise to point out the marketability of certain finishes, but is sound really as unimportant to the builders here as it seems?

Rick Turner
10-04-2011, 06:50 PM
I have to say that sound, to the average music store client...or even the way above average music store client (like Gryphon or Mandolin Brothers, two of my own dealers)...sound is determined by that first look. Yeah, I hate to say it, but an incredible number of "consumers" listen with their eyeballs. Cynical? Me? Yeah... and my cynicism is based on client after client who will bust my balls over the slightest finish flaw before they talk about sound or playability.

That said, I've worked and worked to achieve very thin, very tough catalyzed finishes that are competitive both in appearance and tone. Our epoxy, urethane sealer, polyester finishes are typically about .006" thick, and I believe that is plenty thin enough for decent sound. They're thin enough to move with the wood, so on spruce you'll see the grain lines after a year or so. They're tough enough and glossy enough to put up next to anything in any store. For satin finishes, we use a fantastic flattened urethane over polyester build coats.

I just don't particularly worry about the "tone" of my finishes now. I think the instruments sound fine. I guess you could say that they're designed with the finish in mind, so it's just another element of the tone.

If I were to go back to a one man shop without a real spray booth, I'd probably choose TruOil or Waterlox over two coats of System 3 epoxy sealer OR I'd go with Epiphanes varnish over the same epoxy. As it is, I can do a full finish in three days...rubbed out...if need be, and taking a week is a piece of cake. I do some open pored satins, a lot of pore-filled dead-flat satins, and a lot of full gloss jobs every month.

I fully understand the whole oil finish thing. I also know how crappy they tend to look if not maintained well. I also fully understand that TruOil...like Waterlox...acts more like a varnish than a penetrating oil. I just don't have the time to do gloss TruOil finishes, and the toughness of polyester just amazes me.

I also don't buy into the repairability of nitro. You can touch it up and get it out the door looking great. Six months later the repair sticks out like a sore thumb. And no real world clients will give you the time to let nitro repairs shrink back and settle in so you can rub them out and have the job look good into the future. Sorry, but I've got too many years in the world of retail guitar repair; I know how clients think. They want it all now, and how much time it took for their instruments to achieve such wreckage is not something they're willing to take responsibility for.

Cynical? Actually no. Realistic.

southcoastukes
10-04-2011, 08:06 PM
Rick is undoubtedly correct in stating how many people hear with their eyes. Nonetheless, in this forum, it seems like sound should enter into a discussion like this at a little higher level.

I'll admit, this is a pet project of mine. I worked for a finish manufacturer for a number of years, and happened to be part of the development of a musical instrument finish. Not knowing anything about instrument design (this was 30 years ago!), I was really impressed with the results of our work in terms of sound.

We had no specific protocol for testing, just our own evaluations of workability, rubbing properties, etc., combined with the evaluations of a sizeable number of builders of various kinds of instruments who tested it for us it with an ear as to how it affected their sound.

The reaction was surprising to say the least. We didn't expect to hear how many luthiers had such positive reactions in regard to improved sound. In a number of cases, they said it was something they hadn't considered much before, but certainly would in the future.

Since then, I've always liked to experiment in this, and I think the finish can make a lot more difference than most would imagine. The common idea is that you just don't want it to interfere with the sound - that the best possible sound comes from unfinished wood. I think certain finishes can go way beyond this - that they can actually enhance the sound.


... I guess you could say that they're designed with the finish in mind, so it's just another element of the tone.

That little throwaway line by Rick is key. In my experience, some finishes will work better on some size instruments and certain woods than on others. I'll go so far as to say you can actually improve characteristics like sustain, and use finish to balance or accentuate certain tones.

Anyone else hear this?

Michael N.
10-05-2011, 03:24 AM
I think the common thought is that finishes add mass and/or dampen. Both of which are extremely important when we are referring to strings that are made of Gut or Nylon. Neither of them have the potential energy of steel. In other words it's hard enough to set a soundboard in motion.
The difference (i think) with a Ukulele is that the timbre is very much tilted towards the high frequencies. I'm guessing that there must be a reason why high density woods are used for the soundboard - as opposed to larger instruments where you hardly ever see anything but light softwoods.
I've seen very little in the way of evidence on the effects of finishes on the tone of an instrument. Plenty of anecdotal stuff though. The problem with that is you will arrive at the conclusion that every finish is harmful or every finish enhances the tone. It doesn't matter what that finish is, someone somewhere is going to decry it or shout about it from the roof tops.
The only scientific research I've seen has been done on Violins. The Violin is a very different animal to any plucked instrument though.
It would be nice to hear of some double blind tests, carried out on instruments with different finishes and that have been made with consecutive cut wood etc. Doing something like that though probably requires serious funding. Even then the results are still somewhat subjective. You can easily reach the conclusion that says things are 'different' rather than 'better'.
It's a complex subject, that's for sure.

Rick Turner
10-05-2011, 04:41 AM
Michael has a lot more experience here than most of us when it comes to bowed instruments. I do know enough about them to know that the varnish is a key element in controlling the tone...and yes, that is with damping down excessive high frequency energy. The unchallenged "common knowledge" in the guitar world is that guitars with the thinnest finish sound the best, but is that really true? How do we know that? I'm not so sure it is true as an absolute.

The other "common knowledge" which seems to be fading into the background is that poly finishes don't "sound good". Yet more and more medium and high end guitar companies are using urethanes and polyester at least for sealer and build coats with nitro lacquer being only used for the top three coats that get rubbed out. Bourgeois, Larrivee, Collings, and even Charles Fox went this route; and now Taylor and Larrivee are all poly. With poly undercoats, you get to say "nitrocellulose lacquer" (a somewhat misleading claim), you get that burnished (and easy to do) buff on the surface, and you get a lot of the speed of poly with only needing time for those last three coats. You also get a nitro finish that won't sink into pores.

With regard to high gloss guitar finishes, I think that it would be incredibly difficult to tell the sonic differences among any of the now-commonly used finishes if they were all done to the same thickness, plus or minus .002". I just don't think much difference could be heard between nitro lacquer, polyurethane, polyester, and a hard varnish. So then it comes down to speed and ease of application and marketing spin... Strings and string age are far more important...and less fun to talk about.

Rick Turner
10-05-2011, 04:42 AM
OH...I do think that a French polished top...with an incredibly thin...say, under .002" thick finish...is going to sound different. But there's the most store-unfriendly finish of all...