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I’m talking about the branded Tru Oil. I’ve done one guitar with it, a few back, but realize in retrospect I was applying it WAY too thick.

I’m not going for a “under glass” type finish with this one, but rather a simple and even semi gloss (although I have seen really high gloss tru oil finishes).

Here are some basic concepts I understand about using this finish method. Please correct me if I’m wrong.
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- finish sand up to...600? Or will 600 inhibit the finish by burnishing the surface?

- never apply a 100% mixture but start with 20% mineral spirits applying a very thin, almost dry coat and allow it to soak into the wood.

- allow to dry 3 hours between coats

- apply 4 coats before LIGHTLY leveling with 0000 white pad

- after each leveling drop the % of TO and up the % of mineral spirits.

- after the final coat / leveling process apply a “glaze coat”
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This is just how I’ve grasped the concept thus far... any direction is appreciated.
I’m still a while from starting the finish, so I have time to let my brain grab hold.

* I’ll be happy to post pics of the process if it will help future readers


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I'm just gonna sit in on this thread and watch. I've only used TO once and was very happy with the results. I also found that thinning it was important.

No doubt I will receive a lot of flak over this, but instrument finishes "traditionally" sit on top of the wood and are not designed to "soak into the wood". Having a drying oil soak into the wood changes the whole concept of the WOOD making the tonal sound.
If you insist on using gun stock oil to finish your instruments, a few sprayed coats of shellac or spirit varnish would seal off the wood from the tone robbing oil. Sprayed shellac hits the wood nearly dry, takes literally seconds to dry to the touch and does not penetrate like oil.
I have done this with mandolin finishes of oil/spirit varnishes for years. You spray several light coats of spirit to seal the wood, build with oil varnish and finish with spirit varnish. Lacquer dries almost as fast, especially when the first few coats are thinned.

I won’t be giving anyone any flack:) and, I don’t insist on doing anything in any particular way.
One reason I was considering this was because my last instrument I did use lacquer (em6000). It came out ok, and looks fine, but I wondered how many tone robbing factors I introduced by laying a coat on top of the vibrating surface.
Being fairly low tech I’m not able to say with any certainty how thick it was applied.

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Question: if I were to lay down shellac first to keep it from soaking in, wouldn’t it inhibit the mechanical bond to the instrument?

Haans, your thoughts, suggestions, and wisdom are always appreciated:)


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Your process seems pretty sound. I don't see a problem with sanding with 600 grit before you start, that's what I do on mine.

However, I don't think you need to cut it with Mineral Spirits. Tru Oil applies just fine straight from the bottle. You are correct in fact that you shouldn't just glob it on, it needs to be applied in thin, consistent coats and then scuffed level every so often.

Be careful when leveling, I wouldn't even call it leveling. It is more of a scuff or a buff. TO goes on so thin you never really establish much of a thickness to your finish.

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-Marcus
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When I used tru oil I applied it like padding lacquer or french polish, with a pad. I applied it unthinned, straight out of the bottle. It didn't sink in any more than shellac would and after the first thin coat was dry the rest sat on top. It was a slow building finish, and I only ever took it to a satin sheen. It was easier than french polishing shellac.
I have seen tru oil gun stock finishes taken to a high gloss, but I don't know the method used.

Haans has forgotten more about instrument making than I have ever learned. I have tons of respect for his experience. I take what he wrote to mean that he has put oil varnishes over sealed shellac surfaces without issue. Haans, correct me if I misinterpreted. I'm sure his track record for it's success is well established. I have only done tru oil over shellac once about 7 years ago. it was two wiped on coats of shellac under true oil. It has held up fine.

I do wonder though, just how much tru oil will actually penetrate, say, a spruce top. I bet it would penetrate more than a sprayed shellac base but I wonder if sealing with light and thinned coats of tru oil would keep it to an acceptable minimum of soaking in. Just thinking out loud.

Edit:
Clay posted while I was typing. . .

I think the gloss on gunstock finishes just comes from many, many applications. The one time I used it on an instrument I got a pretty glossy finish after a while. It was some sort of African mahogany I put a lot of very light coats on. I got to a build that had the pores about halfway filled if that gives any idea of how many applications.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Tru-Oil is really kind of mis-named, making people think it acts like a penetrating oil finish. It is really more of a thin varnish which builds mostly on the surface.

I also think sanding to 600 grit is counterproductive. Going up to 220 or 320 is sufficient to remove the visible scratches that show up under the finish.

Tru Oil over shellac (shellac had the color in it). One of my earliest efforts, its about 20 yrs old. Holding up just fine. Tru Oil was not thinned.

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Steve Smith
"Music is what feelings sound like"

I have used TruOil on three of my four barnwood electric guitars. I felt that it gave a nice warm semi gloss finish that was fitting for the hundred year old pine, but I would not want it on wood that I was very proud of. Obviously your milage will vary.



What I did learn is that it is very much like doing FP - you apply many very thin coats, let it cure thoroughly before you can buff it. It does seem to highlight any flaws (read sanding scratches) in the parent wood. I believe that the guitar in the picture above has about 24 coats. I did not apply shellac or any other barrier - I know that TruOil does have something they recommend. Also the finish was apply directly from the bottle, but very very thinly (that 24 coats is probably half a bottle or less).

Others seem to really like it, but it would not be my choice on a fine acoustic.

If you think TruOil soaks into the wood - you haven't used it. Watco danish oil WILL soak into the wood. And I've never heard of anyone complaining about it "robbing tone". I mean, PLEASE.

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"Act your age, not your shoe size" - Prince

I can see how a “laden” top would move differently.


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There is a sealer and filler by the same company. I’ve never put my hands on it though



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I did look back and find the last guitar I finished like this....
as I say, I think it came out ok, but I laid it on too thick... and didn’t allow enough time between coats to really dry before scuffing / leveling


This was during the process with no buffing at that point


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The advice I got from Addam Stark regarding necks was to almost polish the wood, 600 grit at least, and then wipe on a tinted oil based paste pore filler. That fills pores and tints the polished wood.

Follow with wiped on coats of Tru Oil very thin. You need to rotate the piece in the light to be sure you got any runs. They can be hard to see. I usually went 9-10 coats very thin allowing 24 hrs between each.

Worked quite well. The old LMI catalogue/instruction book had a section on TruOil and the guy that wrote it went to 600 as I recall.

I have sprayed tinted shellac and followed with Tru Oil. I had to refinish the back on a +/-1914 Gibson harp guitar and Tru oil over tinted shellac mimicked the original finish pretty well.

Not sure I would use it on spruce without a shellac barrier coat.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

The first dozen or so ukes I made were all finished with Tru Oil (I usually use just shellac now). As you can imagine, this gave me some experience of sanding back to bare wood (!), and I can confirm that Tru Oil sinks in little, if any, more than shellac.

The technique I learned is to wipe on just enough to cover the surface, and after 30 seconds or so wipe off any surplus. Three or four hours between coats, sanding/wire wool (very, very lightly) every four or so.

Spruce is a problem not because Tru Oil sinks in deeper, but because it usually absorbs differential amounts, leading to blotching. Here I used a couple of wiped on coats of shellac first (very light, or that can blotch too)

Any finish - even TruOil - works best applied in thin coats and letting the finish dry between coats. You cannot hurry a quality finish.

_________________
"Act your age, not your shoe size" - Prince

I don't find Tru-Oil to have much penetration. I've taken sections of spruce and side/back woods that I've finished with Tru-Oil and cut them to look at any penetration through a magnifying glass -- not much to see there (the end grain is, unsurprisingly, a different story).

I always thin Tru-Oil about 20% or so with naptha. If I don't, it dries too quickly and doesn't level well; if I do, when it dries there's very little solid material left, and what remains is remarkably uniform. Sanding (meticulously with the grain) to 320 before the True-Oil is entirely adequate for a smooth result, though I'm never looking for a glassy (plastic?) surface. Before the 320, I pore fill the neck, back, and sides with AquaCoat (usually 2 coats), so the pores and grain lines are mostly filled but the wood nature still dominates the character of the final finish -- with glossy wood areas between residual pores and grain lines.

I usually apply 2 or 3 coats in a day, using my fingers and coffee filters, and then hit it with synthetic steel wool (with the grain) the next morning. For the first 2 days, that's the green stuff (0 or 00?); after that it's with the white (000 or 0000?). I've tried continuing the process for a couple of more days but it doesn't seem to do much so I now generally call it quits after 3 days (6 to 9 coats). Then I let it "cure" for 2 days and polish (with the grain) using the white synthetic steel wool. And I'm done.

I like Tru-Oil for several reasons:
-- no spray equipment, spray mess, or spray skills required
-- low labor (compared, for instance, to French Polish)
-- quick dry to tack free, so no dust catching issues
-- incremental glossiness, so continue until satisfied
-- easy and invisible touch up without any witness lines

This last point is major for me. On my last build, I was really disappointed with the feel of the neck near the nut. I had tried a new shape of headstock and fairing into the neck shaft, and after I had strung up the guitar and played it for a couple of days, I was not happy. So I got out the drawknife, files, and sandpaper and reshaped around 10 square inches of neck and headstock. After sanding to 320, I refinished that area and its surround using my Tru-Oil routine. The "repair" is invisible.

One more point: the thinned Tru-Oil, even with multiple coats, results in a very thin finish that can easily be worked into tight corners. Because of that, I can glue on the bridge before finishing. That means no scraping back the soundboard to get a good gluing surface.

I've used TruOil extensively, here's my sequence:
As with any finish, surface preparation is key, and even more so with TruOil. I usually sand the wood to at least 600 grit, 800 to 1000 on woods that will take that much polish. The smoother surface seems to make the woodgrain more articulate, and enhances any 3D appearance. I've never had any adhesion issues going that smooth with TruOil.

The pores need to be sealed, but not necessarily completely filled before you start the TruOil, I typically brush on a couple of coats of 2# cut shellac, and sand back to wood. This does not fill the pores, but it does seal them. It also shows any faults in the surface prep that need to be corrected before starting the oil. You don't have to sand back to bare wood, but I prefer the appearance of the oil directly on the wood. You also lose most of the effect of sanding to higher grits. If you do sand, you need to get all the shellac off or it will show.

I apply by dipping a finger into the oil and spreading it around with the heel of my hand. It's strictly a "feel" thing to tell when there's enough oil to keep rubbing, and when to move on before it gets tacky and will not level out. I break the top/back into 6 areas and do them one after the other initially, and as more oil goes on I cut that down to 3, and for the final coats I do the entire surface. Heating the oil to about 120°F helps getting it to go on thinly and evenly, and is more important after the first 6 or 8 coats. Until there's some oil on the surface, it's difficult to cover the entire surface before the oil starts to get tacky. With the pores sealed, the first 6 coats of TruOil will fill them. The first couple of coats will take a bit more oil to seal the wood, unless you left the shellac. Once it starts to shine a little after it dries (usually 3 or 4 coats), you can use less oil and work larger areas. I put the TruOil on very thin, at least 4 hours between coats. Every three or four coats I'll let it dry 24 hours and level sand, starting with 400 or 600 grit, and working my way up.

Application is very similar to French Polish as far as the feel required. When I get 16 to 20 coats, and have level sanded with 1000 grit, it's almost done.
The last coat has to go on perfectly, with the entire surface getting a very thin coat and nothing getting tacky while I'm rubbing, and then I'm done. I don't sand back after building the finish as is typically done with a nitro finish. This method produces a "soft gloss" which I prefer over the appearance of nitro. I may do a little hand buffing after it cures for a while, depending on how it looks.

I've found it works better if you stretch it out, there's less shrinkage if you allow more drying time during the application. I'll frequently wait 3 or 4 days to sand back, 24 hours is a minimum. I usually take at least a month, sometimes six weeks, to do a finish. It's probably only 4 hours of actual time spent, and can be done in a week, but there will be some shrinkage, similar to nitro. Nitro is sanded back, and you can also do that with TruOil, but I wouldn't advise it. It's thinner than nitro, and getting it thick enough to sand back would take 40 or 50 coats.

Do NOT wetsand at any point after you start the oil, use dry paper on a block. Wetsanding will usually guarantee witness lines.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

I am in the habit of wiping a thin coat or two of shellac on bare wood under any finish I use on furniture, woodwork and guitars. I recently built a walnut table with 2 drawers that had faces made from the cut out areas so they were an exact match. I forgot to shellac the drawers and then varnished everything. The drawers are obviously different, and not as attractive - the grain did not "pop" as they say.

I have used TrueOil on a couple of instruments - about 9 coats total. It looked like the finish was thick, but when I went to scrape the area under the bridge, it was remarkably thin. The first picture below is an Osage Orange ukulele and you can see how thin it was. I did not fill the grain first, so you can see the TO in the grain a bit - very thin.

The second shot I got off a forum (maybe this one) a few years ago. It is a clipboard hanging in the finishing shop at Martin showing how they finish sand each type of wood. Many woods only go to 220 machine sanding, and only a couple of exotics go to hand sanding 320. At the top it says "Note: do not sand with 320 grit on any body that receives a hand rubbed stain"

Ed

I’ve used true oil on a number of instruments and fine woodworking projects. 600 grit is a minimum. Polish the wood before you apply finish.



There is zero finish on this table at this point. The Walnut was sanded to 2000 grit at this point. After 600, the remaining grits go quickly. You can pore fill with Z-Poxy or the like before you get to the 400 + grits. Or you can wait till the end and use Tru-Oil’s filler or an oil-based filler wiped onto the surface (but it can be a pain with guitars and light purfling and bindings if using a dark filler). From there, I apply finish from the bottle un-thinned and fairly liberal to give a nice coat. Then, and this is the trick for any oil-based wipe on finishes in my opinion, grab a fresh rag or shop towel (some recommend using coffee filters, which work just fine too), and wipe everything you just put on off. The finish will build despite your best efforts to wipe it all off. Seems counterintuitive, but it’s by far the best method to a nice looking finish with basically zero additional work past rubbing the final coat out with some 0000 wool (use the synthetic pads) and a bit of wool lube for a wonderful hand rubbed semi-satin sheen.

One final word to the wise - Seal any oily woods with shellac before you start applying Tru-Oil. If you don’t, you run the risk of have spots where the finish never fully hardens and you wind up with a mess. Ask me how I know.


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Aaron Craig

I have finished my last three guitars with tru-oil and am quite happy with the results.
My methods are a bit different than discussed here because It is also my pore fill. I can usually put on 3-4 coats a day, so a week or so if I stay at it, usually 2 with other commitments.
I would guess I apply 25-30 coats, sanding every 4-5 coats, with 220, increasing the grit once pore fill is achieved. Wet sanding to 2000, then applying a thinned coat or two for a final so it lays down very flat. The coats are very thin, wiped on with an old tshirt. Lint and dog hair has been my worst enemy, need to find a good lint free rag.

A few pics

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My memory is so good, sometimes I remember things that never happened.

I first tried Tru oil around the year 2000 - on my personal guitar. It held up pretty well but then again I'm careful with instruments. Don't expect it to be as hard as shellac - it isn't, I've tested it against a few finishes on ebony (less chance of compressing the underlying wood). Nice looking finish, doesn't take much to refresh it even when it does wear. With a UV light box I could get 8 or 9 coats on in a day, more if it's a long day. I don't use tru oil now (long moved to brushed spirit varnish) but I wouldn't have any problem using it for my own guitar again. In fact I'm in the process of building a vihuela for myself and I do intend to use tru oil. Commercially? I'd have to think on it but only because some people might expect a harder finish.

I MEAN PLEEZE...
You have no idea what I am talking about. OBVIOUSLY, I was talking about spruce. A sprayed fog of several coats of shellac does not penetrate nearly as far as smearing a drying oil into spruce.
You know, I have seen your ridicule of many that have asked innocent questions and your self aggrandizing, ego driven answers get rather embarrassing to some of the rest of us trying to help answer those questions in a reasonable, helping manner.
Come to think of it, I cannot think of any acoustic instruments or 2x4's with pickups that you have ever shown us that you have personally built. All you seem to be able to do is make these bizarre comments like "You can't hurry a quality finish" or "You mean besides planning for it first? " or "I've never heard of finish robbing tone", etc, etc...
Moreover, you seem to put up quite a fight over differing opinions from your own. It's as if you ONLY have the correct answers and someone that offers an opinion that differs from your VAST reservoir of knowledge is a fool and you resort to ridicule to try to make your point.

Bryan, you were right in your thinking about what I was trying to say. Thank you for trying to restate it. Yes, a light sanding will make the bond.
The reason I can tell you how finish robs tone is because I have built lots of F & A mandolins and mandolas that you string up in the white and then again after finishing. There is quite the difference in tone, and certain finishes applied in a certain manner will make a better sounding instrument.

Haans, a question here born of ignorance:
When a finish changes the tone of the wood is it because of the weight / mass of the finish or is it because of soaking in? Or is it both? Or maybe it is the added mass whether it is soaked into the spruce or lays on top... I suppose adding anything to the guitar has to change it somewhat...

Also have you found pore filling the back and sides changes things? Or maybe it doesn’t Chan thing enough enough to measurable.


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