French Polish or Bust?

Construction and repair of Classical Guitar and related instruments
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James Lister
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Post by James Lister » Fri Feb 16, 2007 12:55 pm

jebejava wrote: I'm going to refinish the top an old guitar soon and was going to do a french polish.

Is there a particular brand of oil finish you would recommend or is it your own recipe?
I use Rustin's Danish Oil - it's basically tung oil with some additives - mainly to improve hardening. There are other oils you can use, but I haven't experimented much - the Danish oil works pretty well for me.

James
James Lister, luthier, Sheffield UK

ewok

Post by ewok » Fri Feb 16, 2007 2:23 pm

Hi, James,

Do you use shellac to seal the pores before applying oil finish? It seems that oil finish will penetrate into the wood and take longer time (near forever!) to dry.

Jim

jmdlister wrote:
jebejava wrote: I'm going to refinish the top an old guitar soon and was going to do a french polish.

Is there a particular brand of oil finish you would recommend or is it your own recipe?
I use Rustin's Danish Oil - it's basically tung oil with some additives - mainly to improve hardening. There are other oils you can use, but I haven't experimented much - the Danish oil works pretty well for me.

James

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James Lister
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Post by James Lister » Fri Feb 16, 2007 4:24 pm

ewok wrote:Hi, James,

Do you use shellac to seal the pores before applying oil finish? It seems that oil finish will penetrate into the wood and take longer time (near forever!) to dry.

Jim
No I don't - the oil finish does penetrate the wood, and that's fine. I usually sand the surfaces pretty fine so it doesn't penetrate too far. I know some luthiers use a caesin solution to reduce the penetration - particularly violin makers.
The oil dries fairly quickly, but it does take a long time to fully harden.

James
James Lister, luthier, Sheffield UK

StaticXD00d

Post by StaticXD00d » Sat Feb 17, 2007 12:50 pm

Do you do any wet-sanding to fill the pores?

It's not guitar making, but I'm also into building muzzleloaders, and one of the tricks I learned to get a really nice, smooth surface with an oil finish was to wet-sand the stock with thinned tung oil using about 320-grit. As you sand, the dust mixes with the thinned tung oil and makes a sludge, which you then gently wipe across the grain. The sludge fills in the pores of the wood. Let dry 24 hours and repeat until the surface is as smooth as glass, then you can start building up layers of finish if desired, although not necessary, as you will have a good hand-rubbed finish that has soaked into the wood well due to the thinned oil by the time you get the pores filled, which usually takes 3 or 4 sandings to accomplish.

On woods like maple which aren't very porous, you may only need to do 1 or 2 sandings. On something like walnut which is extremely porous, it takes more, but the end result is stunning.

Was just curious if anyone did this when finishing guitars with an oil finish. Obviously if you're just gonna spray the instrument with 20 coats of lacquer there's no need as that will fill the pores nicely in itself.

It's funny on the luthier forum you don't hear comparisons to gunstock finishing, but on the gunstock finishing forums (and probably others like furniture too), you are always hearing someone compare a finish to an instrument like a violin or a guitar.

bones

Post by bones » Sat Feb 17, 2007 1:07 pm

I've recently bought an excellent 'Hauser type' model from James and it is finished with Danish Oil and then has a coating of wax applied, the finish could be described as a 'sheen'. This is firstly very good for the sound (most important) and is aesthetically pleasing, secondly it is easy to maintain by the player, just a polish with wax now and then. I have owned French Polished guitars and laquered, I like the finish of both but french polish is hard to look after I find. If spending a lot of money on a luthier model the only laquered finish guitar I would probably buy would be Ramirez, although I'm open to all instruments, cash allowing! Schramm guitars have a very fine French Polished finish.

jebejava
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Post by jebejava » Sat Feb 17, 2007 1:57 pm

I have used the same process as StaticXD00d describes when doing an oil finish - wet-sanding with the finish to create a slurry that works as a pore filler. The finish I've used is Watco danish oil, but I stopped using it a long time ago due to the fumes. The current formulation is different though.

Over on the Musical Instrument Makers Forum (MIMF), Tru-oil has been popular as an oil finish for instruments and perhaps StaticXD00d is famliar with it as it is popular in the gun-makers' world. However, I have not tried it. In recent years, I have been using Bartley Gel varnish for my woodworking and the results are excellent. I refinished a guitar neck with it and it feels very good and after over a year, durability is excellent.

Both Tru-oil and Bartley are described as "varnishes", why they are varnishes I do not really know. This much I've observed in using Watco vs. Bartley. Watco (described as an oil finish) is absorbed into the wood, but Bartley more or less stays on top. As an instrument finish especially for tops, it seems to me that Bartley is a finish to try. Perhaps I'll use it on the top that is due for refinishing.

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James Lister
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Post by James Lister » Sat Feb 17, 2007 2:03 pm

StaticXD00d wrote:Do you do any wet-sanding to fill the pores?

It's not guitar making, but I'm also into building muzzleloaders, and one of the tricks I learned to get a really nice, smooth surface with an oil finish was to wet-sand the stock with thinned tung oil using about 320-grit. As you sand, the dust mixes with the thinned tung oil and makes a sludge, which you then gently wipe across the grain. The sludge fills in the pores of the wood. Let dry 24 hours and repeat until the surface is as smooth as glass, then you can start building up layers of finish if desired, although not necessary, as you will have a good hand-rubbed finish that has soaked into the wood well due to the thinned oil by the time you get the pores filled, which usually takes 3 or 4 sandings to accomplish.

On woods like maple which aren't very porous, you may only need to do 1 or 2 sandings. On something like walnut which is extremely porous, it takes more, but the end result is stunning.

Was just curious if anyone did this when finishing guitars with an oil finish. Obviously if you're just gonna spray the instrument with 20 coats of lacquer there's no need as that will fill the pores nicely in itself.

It's funny on the luthier forum you don't hear comparisons to gunstock finishing, but on the gunstock finishing forums (and probably others like furniture too), you are always hearing someone compare a finish to an instrument like a violin or a guitar.
Interesting... I haven't heard of this being done by luthiers. I might give it a try, although I must say I do quite like to see the grain of the wood. Even when I french polish, I don't normally fill the grain, unless specifically asked to.

James
James Lister, luthier, Sheffield UK

StaticXD00d

Post by StaticXD00d » Sat Feb 17, 2007 2:25 pm

jmdlister wrote:
Interesting... I haven't heard of this being done by luthiers. I might give it a try, although I must say I do quite like to see the grain of the wood. Even when I french polish, I don't normally fill the grain, unless specifically asked to.

James
You won't lose any grain using this technique, you'll simply fill any open pores with a fillter that is the same color as the wood, since it is made from the sawdust of said wood. It will not affect the look of the woodgrain at all.

And yes, jebejava, I am of course familiar with Tru-oil. I built a little flintlock pistol a year or so ago with a walnut stock. I filled the pores using wet-sanding with Formby's Tung Oil Finish thinned down with mineral spirits (4 parts MS to 1 part TO). Once that was done, I hand-rubbed about 6 coats of Tru-oil on top of the tung oil. Turned out very nice.

If done properly, Tru-oil can be made to look like a very glossy, sprayed-on urethane or varnish. Tung oil will work nicely for a more satin, less shiny finish. I think both would work great as a guitar finish, depending on what you want to end up with.

jebejava
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Post by jebejava » Sat Feb 17, 2007 2:57 pm

Static, you've inspired me to keep disco evil and unmoving :) and I'm going to use Tru-oil to refinish that top when spring comes.

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Post by James Lister » Sat Feb 17, 2007 5:39 pm

StaticXD00d wrote:You won't lose any grain using this technique, you'll simply fill any open pores with a fillter that is the same color as the wood, since it is made from the sawdust of said wood. It will not affect the look of the woodgrain at all.
Sorry, poor use of terms - I really meant that I like to see the open grain - i.e. the pores. Still, I will try it some time.

James
James Lister, luthier, Sheffield UK

StaticXD00d

Post by StaticXD00d » Sun Feb 18, 2007 1:46 pm

Ah, understood. Well, depending on the type of wood, you may or may not still see them. I know on walnut, you can still see them, you just can't feel them. I would think that unless the piece of wood is all exactly one single color, you would still see them, because the slurry you're filling them with won't exactly match the wood surrounding the pores, but it will be close. On walnut, it tends to make the pores darker than the surrounding wood, so the pores still look like little dark freckles on the stock.

Let me know how it works out for you. I would definitely be interested to hear how it works on woods that I have not yet worked with. (Most gunstocks are either walnut or maple, so I've not done this with cedar, spruce, rosewood, mahogany, etc.)

John

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Post by James Lister » Mon Feb 19, 2007 9:47 am

I'll give it a go some time - what ratio do you use to thin the tung oil?

James
James Lister, luthier, Sheffield UK

StaticXD00d

Post by StaticXD00d » Mon Feb 19, 2007 12:56 pm

Pretty thin... about 4 to 1 mineral spirits to tung oil. Thinning it makes the slurry easier to deal with as it's not as thick and gooey, and it also helps the tung oil soak deep into the wood for good moisture sealing and protection. (Something that is obviously important on a firearm one will be trapsing through the woods in all sorts of weather with.)

Once the wet sanding is done, I'll still thin the oil down about 2 to 1 mineral spirits to tung oil for adding finish layers. Seems better to add more very thin layers and build up a finish than to add just a few thick layers. I do this also with the Tru-oil if I'm using that. I hand-rub the oil in small sections with my fingers until it starts to get tacky, then wipe off any excess and let dry for a day. Repeat until satisfied.

I would like to try the Watco stuff, but just haven't bought any yet, however, it has come highly recommended by other builders I've spoken with and read about.

P.S. I checked out your website... you make gorgeous instruments. I really like the one with the contrasting wood for the rosette... beautiful. You are obviously a talented craftsman.

bones

Post by bones » Mon Feb 19, 2007 1:20 pm

StaticXD00d wrote:
P.S. I checked out your website... you make gorgeous instruments. I really like the one with the contrasting wood for the rosette... beautiful. You are obviously a talented craftsman.
You should hear how good they sound too, 'Fidelina' is only a few months old and she seems to sound better week on week. The headstock design in particular is the most gorgeous I have seen.

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James Lister
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Post by James Lister » Mon Feb 19, 2007 2:20 pm

bones wrote:
StaticXD00d wrote:
P.S. I checked out your website... you make gorgeous instruments. I really like the one with the contrasting wood for the rosette... beautiful. You are obviously a talented craftsman.
You should hear how good they sound too, 'Fidelina' is only a few months old and she seems to sound better week on week. The headstock design in particular is the most gorgeous I have seen.
Thankyou both for your kind comments - very encouraging when the order book is not as full as I'd like it to be!

James
James Lister, luthier, Sheffield UK

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