Finishes

hello all,

Have built 2 tenor size instruments which got good reaction from the recipients. (they're pretty talented musicians) Obviously I'm now hooked and am going to build some more. I sprayed can lacquer on the first instruments with wet-sanding between coats. The finish looked as good as I would wish it to look.
My question is probably pretty common. What's the best finish as far as sound qualities? It seems likely that some approaches would detract from the soundboard's ability to perform. Would all of these instruments perform best if they weren't finished at all? If the finish is primarily a protective preservative, why aren't we applying some on the inside too? Any house painter would tell you that wood lasts longer if you paint the back side before you nail it onto the house. The differential moisture absorption rates are what causes wood to warp and twist.

I'm basically looking for a simple but correct finish approach that won't compromise the sound and tone of the instrument.
If there are previously posted discussions of this topic here, I'd appreciate a lead to them.

Thanks,

Ron B

Take your pick below. Don't get caught up with the 'best finish for best sound' thing. Wait a decade for that when your instruments are consistent enough to maybe hear it on a blue moon,...with a spectrum analyser.

~ Finishes you need a rag for
Shellac/French polish
Tung Oil rub

~ Finishes you need equipment for
Nitro
Poly etcetcetce

Keep the finish thin. That seems to be the considered opinion. Many instruments that are made in a factory setting are very thick spray coatings that are designed to cover every single blemish of the wood.
To add to the above: Brush or sprayed.

Spirit (shellac based)
Oil Varnish (there are numerous types). Perhaps the one that really does show wood at it's best.

PS. The inside isn't (usually) finished simply because it isn't necessary. 4 or 5 hundred years of stringed instrument making tells us that, despite what the house painter says. Pretty hard to argue with that amount of experience.

Who said we don't finish the interiors? I'm with the house painter on this one and so are many of my peers. Tradition be damned, I always seal the interiors of my uke bodies. I have found it beneficial on many levels.
When considering types of finishes to use you need to look at what end result you are comfortable with, what your production level is, how concerned you are about your health, how much time you are willing to spend (and charge for) what kind of equipment you have or are willing to buy, what local regulations are concerning those types of finishes, etc. Knowing those parameters will be helpful in narrowing down your choices.

IMO..Chuck Moore does the best Nitro finish in the Ukulele world...my Milo/Spruce uke is unreal....nobody close...and the inside is nice too!!
Rick Turner does the best Polyester Gloss I have seen

btw Ryan who works with Noa at Ko'olau very good too..with nitro finishes...

but if the ukes don't sound great(like the guys above)..all to waste

my 2 cents...

Thanks guys. This is all very helpful. I might give the insides of the next builds a light spritz of sealer, though it occurs to me now that doing so without getting any on the surfaces to be glued might be complicated. I can see the point about keeping it thin since the wood's ability to vibrate has to be affected eventually. Picture 6 coats of house paint on a 1/16" soundboard. Also, intuition tells me that an oil that penetrates might make the wood "soggy" rather than "brittle". That concept also makes me wonder about grain fillers and whether filling the pores is a negative step. I'd really like to investigate waterborne finishes since I work in the cellar, and the finishing process inevitably allows some smells to get upstairs. It's likely I'm overthinking this, but there's a lot of time and effort involved, and a bit of research is worth it.
Any thoughts on odorless/low odor/ waterbased finishes would be appreciated.

Thanks,
Ron B

I've tried most of the finishes suggested in this thread, and in my experience, the best finish for the home-based, hobbyist builder is Tru-Oil. It is forgiving in its application, requires no special tools besides a clean rag, goes on thin, doesn't spew highly toxic solvents into the air, and makes an attractive satin finish. With that said, lately I've been spraying nitro in a homemade booth vented through a window, mainly because I'm a masochist and prefer a glossy finish.

If you want to aim towards really nice finishes, I think waterborne finishes are not a great direction to go. They are not as friendly to work with as nitro, I have not used one that rubs out as well as good nitro, like Cardinal, and the color rendition over wood, in my experience, is terrible. Seconding what I understood Michael N. to say, oil varnish may be tops as far as bringing out the best in the color of wood, and is very friendly to work with once you have a system down. Using shellac as a sealer beneath waterbornes helps with color, but still.. waterborne finishes are a pain, IMO. Some people probably love them though.. French polish is not too stinky, and can be as beautiful as any finish. Actually, for the size of an uke, oil varnish might be a good way to go also, if you want to stay away from nitro. I like nitro for ukes, but if you are starting from scratch, tooling up for safe, professional application of nitro is not cheap, and there is a learning curve.

Hi Ron,
I've been doing small shop application for close to 30 years and have tried just about every small shop solution possible. There are pluses and minuses to just about all of them; the best thing I've found to use is Minwax satin wipe-on poly. I built and sold many instruments and can tell you that satisfactory results can be obtained with just a bit of practice. You can check out my Tenor Uke build utilizing it here:

http://www.bluestemstrings.com/pageUke1.html

Tru-oil is probably the next best thing but requires WAY too much time due to a slow finish build requiring far too many coats. The other thing that factors into Tru-oil is that I've found it not to offer enough surface protection on a softer wood top such as spruce. My Tru-oiled spruce top instruments always ended up with surface dings and scratches, so I opted to find another product for that reason coupled with the need for too many coats for a good finish build.

This subject is always extremely controversial as there are many different approaches that work, none of them actually easy if you're after professional results. That is to say there is a learning curve. Anyone who has climbed the ladder tends to like the ladder they climbed the best. I have done just about everything EXCEPT the modern technological UV cure variants. And I won't likely try them as I am a traditionalist as well as being an old guy and set in my ways. I started with Oil Varnish and went through nitro and waterborne where I stayed for many years before nostalgia took me back to my roots just for old times sake.

When I first used Varnish, back in the 60's and 70's, I learned to apply it with a brush, not unlike the Yachties do. This works great, and is low on tool requirements as a good brush (that is a can of worms) is basically it. There is a lot of sanding, an under rated skill. A brushed varnish is quite easy to get super thin, like .002, though it may not be as even as wished till that sanding skill is well honed.

When I started back at it I brushed, but having got quite skilled at spraying I tried that out with the varnish. For the last ten years I have never looked back. The negative is that it is messy for the gun. For that reason I favor the Harbor Freight $15 touch-up gun. When it gets ugly (every 12 instruments or so) I just toss it.

If the OP or anyone else is interested in my schedule, email (Not PM) and I'll send you it. If you want a visual sense of it look at the nearby Healdsburg thread.

Thanks again. I sort of knew that the waterborne route was wishful thinking. Never did see it used on a hardwood floor without being disappointed. Too bland looking, and does nothing to warm up the wood 's appearance.
I have used a few wipe-on products for small stuff over the years, and I think I'll focus on that approach. Any spray method just puts too much smell in the air, and I'm not really set up to arrange for a booth and ventilation.

"Progress through experimentation, but don't re-invent the wheel"

or as my first boss used to say, "work fast! we'll need time to do it over"

If I could invent a finish that truly went on thin, was tough and durable, looked good, and gave a professional mirror finish quickly with no effort I'd be a millionaire.....but everyone would poo-poo it for not being traditional.

Following advice from luthiers on this site, I finally tried sanding meticulously, followed by an expoxy grain filler, scraped off with a credit card type item, sanded down from 220 to 6000 (I like the 3M polishing papers best after 600 grit sandpaper). Then Tru Oil, 2-3 very thin, thin coats, with a light once over with the 6000 paper between. I think it dries pretty quickly if you keep it thin. You get a surprisingly glossy finish this way. The Z-poxy is almost odorless, and the tru oil is just slightly musky smell (reminds me of a mink oil, although the tru oil is not truly an oil, from my understanding). No spray booth required, can do it all indoors, although ventilation is ALWAYS good.

Anne

Something else to look at would be Tru oil in a spray can.
I think you would still want to do a wipe on coat of Tru oil or even shellac first to help fill pores and what not, but I find the spray can works very well with virtually no oder at all.
I bought mine at Woodcraft, but I'm sure you could get it online too.

I agree with Anne.
See video here, about my way, with Danish Oil Liberon.
twice grit: 400 - 600 - 800 - 1000 - 1200 - 1500 - 2000 (Tamiya sand papers).
http://www.youtube.com/watch?v=1HKKkvhDN5M
All my ukes are finished like this (pics on my website).
Glassy finish, baby skin touch.
No spray, just open the window 20 mn, it will be ok...
Bye,
Gerard.

afreiki said:

Following advice from luthiers on this site, I finally tried sanding meticulously, followed by an expoxy grain filler, scraped off with a credit card type item, sanded down from 220 to 6000 (I like the 3M polishing papers best after 600 grit sandpaper). Then Tru Oil, 2-3 very thin, thin coats, with a light once over with the 6000 paper between. I think it dries pretty quickly if you keep it thin. You get a surprisingly glossy finish this way. The Z-poxy is almost odorless, and the tru oil is just slightly musky smell (reminds me of a mink oil, although the tru oil is not truly an oil, from my understanding). No spray booth required, can do it all indoors, although ventilation is ALWAYS good.

Anne

Click to expand...

Just a few more thoughts on finishes that I've tried.
Tru Oil. I finished a Guitar entirely with Tru Oil some 12 years ago. I can't remember how many coats I gave it but I think it was well in excess of 20. You can get Tru Oil to a high Gloss finish, it's just not quite as glass hard looking as something like Nitro or French Polish. It's a nicer gloss IMO, a bit more friendly looking. That was my personal Guitar for 10 years. Tru Oil is a relatively soft finish though. No question about it. Providing you are very careful with the instrument it should hold up fine. It won't last forever but then again it's a simple affair to add more coats. 25 coats may sound like a lot but they are quick wipe on, wipe off. To coat a Back would take less than 1 minute. It's already been mentioned: you need a bit of cloth to apply it. It's low in VOC's. Being an Oil based finish it pops the grain.
Danish Oil (with resin). These vary enormously, depending who makes the stuff. The types that contain resin should hold up better than Tru Oil. The Liberon mentioned above contains a resin. Still a little on the soft side, at least the few brands that I've tried were. Again, apply enough coats and you can sand/buff to a pretty high gloss finish. I know because I've done it. You may need even more coats than the Tru Oil. It also has a lot more VOC's than Tru Oil.
Oil Varnish (applied with a brush). Most modern makers who use Oil Varnish are using a variation of a Spar Varnish. Epifanes is fairly common, Captains another. Pratt & Lambert 38 is also used by some makers. They contain a modern resin (either Phenolic, Alkyd, Urethane or combinations) in a drying Oil. The higher the resin to Oil ratio the harder and more brittle the varnish. Behlens Rockhard is one that I've tried. It's been the hardest Oil Varnish that I've ever used and straightforward in use. I disliked the heavy chemical smell and the strange colour caste that it gave to light coloured woods. I only used it once and then went back to using natural resin varnishes. I've also recently tried a pure Alkyd varnish that is more like the old fashioned Yacht types but it's simply too early to give any definitive views on this stuff. So far I'm liking it.
All the above require very little in terms of equipment. Some of them will need adequate ventillation - mostly just an open window. If I was wanting a real simple but fine looking finish I would go with the Tru Oil and accept that it needed some maintenance along the way. If I was looking for a harder and more durable finish I would opt for a short Oil Varnish brushed on finish. Either that or a Spirit Varnish/French polish. The Oil varnish looks better than a French Polished finish in my experience.
Nitro I wouldn't go within 100 yards of. It can look mighty fine but the fumes/health effects are simply not worth it - at least not for me.
Oil varnish and Spirit (Shellac) can both be sprayed but obviously that involves a lot more equipment and VERY good extraction.

Hello again,

I'm really appreciative of the depth of peoples' answers and suggestions. I'm going for a finish that shows off the wood and work, but I don't want people to be afraid to touch it. I've used Formby's wipe-on "tung oil" finish with pretty good results on some small non-instrument projects, and have been pleasantly surprised. I get the feeling that the Tru-oil is a similar system, and I'm going to give it a try. The thought of all of those brushes and spray-guns I won't be cleaning is a pretty good one.

Thanks again,

Ron B

Penetrating oils are generally thought of an inappropriate for instruments because they change the nature of the wood and cannot be removed without also removing wood. I think of Danish and TrueOil in this category. Sealing with epoxy (described above) would subvert this issue, but then you'd be epoxy/plastic coated, which I cannot stand the idea of. Also, penetrating oil are designed to penetrate and be wiped off the surface, so not penetrating means they'd be close to entirely wiped off, which means MANY applications and uncertain results.

Spar Varnish (which I've tried) is the wrong stuff for our purposes. It never entirely dries, stays flexible, and always feels slightly sticky, assuming we mean actual spar varnish as you get in the Marine Chandlery. What we do want is designed to be used in the interior of houses. It used to be called cabinet varnish, maybe still is somewhere. It is not meant to be waterproof, though it pretty much is. There are still a number of makers of this kind of thing, but the reformulation for modern requirements is handled in different ways and often seems to work aginst us. Behlen Rockhard is a good example. I used it for years and then suddenly the next can was a greenish amber color, and took much longer to dry. I am currently (over five years now) using something carried in my corner hardware store called Ace Interior Oil Varnish. It is a non-pretentious product that really does the job, and it's not even expensive! Seal with Zinnser Sander/Sealer NOT Zinsser Shellac which is waxed. Both are spirit based shellacs.

I believe tru oil is not a penetrating oil, and the name is somewhat misleading. And yes, it is a very thin wipe on/wipe off coat, but you don't need more than 3 coats.

Anne

First, my disclaimer:
I've not built a ukulele (yet); I will this Spring. I have, however, built custom furniture for the last 30 years. I've tried all sorts of finishes, including spraying.
So, that being said, shellac is a wonderful sealer/filler. Easy to apply, not expensive, quick drying, allowing a number of coats in a day. As Bruce Sexauer correctly wrote, make sure to use de-waxed shellac for good adhesion with your oil of choice topcoat(s). Shellac has a 'flexible' nature, which I suspect, could help, not hinder, the vibration of the soundboard/top. If one seals/fills the wood well and achieves a nice level surface, then only 2-3 thin applications of oil will give a beautiful finish. We all know each finishing method has it's charms, and detractions; I personally love the warmth, and 'friendliness' of oil over shellac.