Trying to decide on a finish

[Stag]

My first acoustic guitar build. Italian Alpine Spruce soundboard & Victorian Mountain Ash back, sides and neck.

I like the look of an oil finish. I feel a bit wary about an oil finish hearing various reports about a deadening of sound. I suspect the sound of an oil finish might not settle in for years and judging the sound within days or even weeks of applying an oil finish may not be truly indicative.

I'm very tempted by Tru-oil. I have a devil on my shoulder telling me to use my own finish of mostly boiled linseed oil and pure gum turpentine with a little beeswax.

The other option I'm considering is shellac. It seems most tried and true.

Must be matt or satin. Glossy wood always seems wrong to me.

It was easier deciding to marry my wife than commit to the finish of this guitar

Input? Opinions? Experience? Anyone make their own finish?

[kiwigeo]

Experimenting on your first build with your own finish.....wish I had balls of steel like you mate.

[martintaylor]

I use Rustins Danish Oil on my builds. I sand to 1200 grit then I do 6 coats of Oil (rubbed with 0000 steel wool in between each coat). I finish with 2 coats of U-Beaut Wax. It gives a great finish, satin in appearance allows the timber to breathe and if there ever has to be any repair work in the future is the easiest to blend in.

[Dekka]

Shellac the spruce first (several layers and then a light rub back down to 0000 steel wool) and then oil over the lot. I used that Feast&Watson Buffing oil and it came up a treat.

[Rob the luthier]

I have used many types of finish but my firm favourite has to be tru-oil, a lovely natural looking finish and pretty damn tough too...

[Mark McLean]

Hi Stag, and welcome to ANZLF
That idea that oil finishes somehow dampen sound? - smells stongly of bullshit. It is a relatively lighter form of finishing than many alternatives, so it is hard to see why that would be the case. Compared with the effect of different timbers, bracing and construction methods, scale length, string gague, and a million other factors that affect acoustic performance, the difference made by alternative finishes would have to be minimal. I have never seen the data from an experiment where 2 otherwise identical guitars are given different finishes and the difference in sound is objectively assessed (Trevor - have you done that experiment yet? I might have missed that page in the book). In the absence of such information anyone who tells you that there is a difference is probably having themselves on.

So, if we discard that issue - a hand applied oil finish is the ideal option for the hobbyist luthier. Easy to do, no fancy equipment, non-toxic, easy to touch-up and repair when you goof something up, and it looks great (as long as you are not trying to achieve the perfect "my wood is under a pane of glass" finish of a lot of factory-made guitars). You say you want a "real wood" look, and I agree totally with you there.

So which type of oil? There are lots of options and they all seem to work. Danish Oil or a homemade equivalent has been used by lots of folks. Tru-Oil is a perenial favourite and probably cures a bit harder and faster. A lot of people put some sealing coats of shellac on first, and I think that is a good idea (but use a blonde one - the orange shellac from Bunnings will give your Victorian Ash a nasty fake tan look).

Then you will have to make another quasi-political asthetic decision - do I pore fill, and how? That is another can of worms.
Enjoy the fun of your new addictive hobby!
cheers
Mark

[matthew]

That idea that oil finishes somehow dampen sound? - smells stongly of bullshit [...] Compared with the effect of different timbers, bracing and construction methods, scale length, string gague, and a million other factors that affect acoustic performance, the difference made by alternative finishes would have to be minimal.

[Tod Gilding]

That idea that oil finishes somehow dampen sound? - smells stongly of bullshit [...] Compared with the effect of different timbers, bracing and construction methods, scale length, string gague, and a million other factors that affect acoustic performance, the difference made by alternative finishes would have to be minimal.

agreed,

My first 5 guitars were finished with Howards Orange Tung Oil great stuff and any talk of oil finishes being detrimental to tone now or in the future is just bullshit. In fact it is the most preferred NECK finish amongst guitarist very fast necks with oil

[kiwigeo]

Hi Stag, and welcome to ANZLF
That idea that oil finishes somehow dampen sound? - smells stongly of bullshit.

I dunno. People say my guitars sound crude......could be something to do with the oil finish.

[nnickusa]

Tru-Oiled my last one. I'd do it again in a second. It has only been described as bright....And, I left the finish a satin-y one. Love the mellow look on the timbers I used....

I'd say that "the experts," and "they" are usually wrong..... 2c

[matthew]

Hi Stag, and welcome to ANZLF
That idea that oil finishes somehow dampen sound? - smells stongly of bullshit.

I dunno. People say my guitars sound crude......could be something to do with the oil finish.

i'm sure you compensate with slick workmanship ...

[Trevor Gore]

I have never seen the data from an experiment where 2 otherwise identical guitars are given different finishes and the difference in sound is objectively assessed (Trevor - have you done that experiment yet? I might have missed that page in the book). In the absence of such information anyone who tells you that there is a difference is probably having themselves on.

No, I haven't done any experiments on oils; never used them. However, Brian Burns (makes mainly flamenco guitars) swears blind that when he used oil on a batch of guitars it killed them stone dead. Brian's into measuring stuff, damping especially, and I know he has a good ear (he could tell when I pulled the side masses out of a guitar by hearing it from the next room!), so if he says something, it's more likely right than wrong. However, given that wood varies hugely in its damping and we're not all building flamencos, what you hear will very likely depend on the acuteness of your ear, what you're used to, the style of guitar and what woods you used. I used a polyester grain fill on a guitar once. Never again, for the same reasons Brian mentioned. Polyester is VERY high damping compared to epoxy, as anyone who's sailed both polyester/glass boats and epoxy/carbon boats will tell you.

Regarding the use of oil finishes on bowed instruments, I've heard that a certain degree of damping is beneficial and instruments played in the white are over-raucous; but that is just hearsay. I know next to nothing about bowed instruments.

[J.F. Custom]

It probably pays to mention (remind?) here also, on top of what Trevor has stated, that there are many variables to consider making any conclusive statement about oil use a tad difficult.

Some oils penetrate deeper than others. Some oils set hard, while others tend to stay in a semi-permanent heavy/sticky state. Some are heavily modified with cocktails of unknown ingredients, others are more or less natural. Some oils are more polyurethane than they are oil, despite the name etc etc. So 'oil' as a judgement term of "good/bad" is not very concise.

Then there is the application method - how many coats you are applying; did you seal the timber first etc.

Oils aint oils as they say...

Jeremy.

[jeff crisp]

I have a devil on my shoulder telling me to use my own finish of mostly boiled linseed oil and pure gum turpentine with a little beeswax.

Since you've used the word mostly you might already be aware of this but if using a home brew like you've described you will need to add some kind of drying agent like terebine or you'll end up with a sticky mess like Jeremy has mentioned.

[DaveW]

Hi Stag
I think the original idea that oil dampened the wood came from the classical guitar makers who were quite traditional and there reasoning was because it soaks in a bit unlike shellac which doesnt it therefore changed the structure of the wood and its tonal charachteristics
I think as most people here say "its bullshit" it may not be that but I I doubt if I would ever be able to say "that sounds different because its oiled " if I did you can guarantee that would be bullshit!!
anyway I digress I built my first guitar about 18 years ago . a classical ,my second about a year ago ?? this is why I was referring to classical makers and there theory on oil as that is what I read and what I believed must be true ?
so I decided I would french polish my guitar ..............well after months of just ending up with a "gooey mess" I opted for I think it was Feast Watsons Buffing oil which was as it turned out a godsend as it enabled me to finish my guitar .......French Polish ............that seemed to be some sort of torture designed by an unbenevolent god ?
who in there right mind would have ever seen a secretion from a beetle and said "I think that beetle shit will make a fine wood polish ????"
move the clock forward 18 years and the internet and all the info you can get has changed my ideas completely ,I wouldnt do anything but french polish ,its easy ,its relaxing , its easy to repair ,it doesnt involve nasty chemicals and I dont believe there is any other finish that gives wood the same beauty ?
My two bobs worth, French polish it ,if you dont like it its easy to change to oil ,I dont think the other way around would be
Dave

[matthew]

Hi Stag
I think the original idea that oil dampened the wood came from the classical guitar makers who were quite traditional and there reasoning was because it soaks in a bit unlike shellac which doesnt it therefore changed the structure of the wood and its tonal charachteristics

And another non-bullshit reason to be very careful that oil finishes DON'T sink in, in the violin family at least, is that you have no chance of doing any future repair work with oil-soaked wood. At least, not with any of the glues that *I* would use for a valuable instrument. So if a violin (or double bass) luthier wants an oil finish, then the ground coat is critical to seal the wood before application. Some use shellac for the ground coat ... and that's a whole other story.

[DaveW]

I think Matthew has a very valid point that I never thought of !!

[charangohabsburg]

And another non-bullshit reason to be very careful that oil finishes DON'T sink in, in the violin family at least, is that you have no chance of doing any future repair work with oil-soaked wood.

Good point Matthew. I think that the violin family tops are insofar different to "flat"-top guitar tops that the former ones have, due to the 3-dimensional carving, wood fibres that run out of the surface almost everywhere, while the latter ones have relatively few (and sometimes almost no) fibre cross sections exposed to the surface. The only two ways a liquid can soak into wood is that it enters into the fibres before it dries, and via osmosis across the wood cells before it dries or, in the case of for example oil, polymerises. Osmosis of oil into wood is relatively slow, and slows down more as the oil dries, so that the greatest part of soaking happens via entering the exposed cut fibres while the oil is still in its liquid state (this is what I have observed using spruce, olive oil (not a "drying" oil) and a good microscope (not a SEM though ) during some experiments I made about 1 year ago). Even if TruOil dries very quickly, depending on how generously each layer gets applied, it still may creep a little bit (really not much at all) into the opened wood fibres, and even make transparent the outermost (exposed) cell walls. All this is why I think that grounding a violin family top makes perfect sense, but it would be exaggerated to worry about with reasonably runout free guitar tops.

[matthew]

markus if that is the case how then is it that one can stain a guitar top or back without too much trouble? its not just sitting on the surface!

[charangohabsburg]

Do one stain with a fast drying oil varnish?