Official Luthiers Forum!

I know of at least one pretty well known builder who told me he was using an oil varnish/tung oil mixture, I believe, and rubbing it on one coat at a time with a cotton cloth. When examining his instruments very closely I could tell the swirl marks from the cloth were there but overall a pretty good-looking varnished finish with some vintage "vibe" to it. I would even say if he were a little more diligent with the rubbing process they would look pristine. His finishes looked pretty thin and I would even consider trying it but I'm a little skeeeered.

Anybody doing something like this?

thanks for any help.

SR

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"We might not be big but we sure are slow"

I hand rub either tru-iol or rockhard varnish on most all my necks. There are no swirl marks left after leveling and polishing. Even on my French polished neck you would see no swirls. something is strange if the feels smooth and polished but you see swirls because swirls would be signs of unlevelness or comtaminations traped in previous applications.

what are you leveling with and do you sand between coats? Do you have any witness lines when doing the final rub out?

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"We might not be big but we sure are slow"

With varnish you can level after the second or third session cures out if you wish but I apply pretty level to start with and just lightly rough up between coats with 400p and then level after the 8th and final session with 400, 600, 800, 1000 then buff with Menzerna med, med fine, then fine.

I'm a great fan of hand rubbed oil finishes, I've used them on a number of lutes and guitars. The most important thing is to apply each coat very, very thinly. I have had just as good results using ordinary kitchen tissue paper. Just invert the bottle on the paper and before applying go the wood, ensure that the oil has been absorbed into the paper rather than just sitting on the surface. Wipe on with the grain very thinly as I said. Two or three sessions day, until 8-12 coats have been applied, leave to harden for a few day, then I rub out any marks with rottenstone in walnut oil. Buff with auto swirl remover if needed and job done. I have never used abrasives on an oil finish as if applied in thin enough coats no levelling is needed.

Both of these were finished this way.





Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I was going to speak to that as well Colin but I have to leave a tad bit or two now and then to you . Actuall the only varnishing I do is on necks and I never found a way to insure as level build as in FPing so I break my rule on abrasives for varnish finishes. So do you spirit off to level

I am very much not a fan of using a "Danish" oil varnish/drying oil combination on a guitar, and even more so if the drying oil is tung. I would say to use this only if you want a slow drying finish that feels tacky to the hand and is difficult to build to an even film or to a gloss.

These comments do not apply to a short oil varnish, that does not have free oil added.

So I wonder if we are talking about the same thing.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

One of the beauties of an oil varnish (if that is what's discussed here) is the time it takes to cure, thus to self level. It requires a certain technique with a brush, but it's definitely not beyond the skills of somebody who can build a guitar.
Spraying varnish has to be the easiest thing, it really levels itself out and all that is needed is to lightly sand between coats (and get the inevitable specks of dust of the surface). It has none of the drawbacks (and technique required) to spray nitrocellulose lacquer, for example.
Padding an oil varnish seems to defeat the purpose IMHO.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Completely agree Howard, the only commercially available, out of the bottle, oil finish I would consider for a guitar is Tru-oil, there are many very successfully finished guitars using this finish padded on as I described. The finish I use is similar, but made by a bespoke violin varnish maker specifically for musical instrument restoration.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I have used Tru-Oil and micromesh to shine it up quite nicely...

About a year ago or so in Fine Woodworking there was an article about varnishes where the author mixed Pratt & Lambert Gloss 38, a little tung oil to give it padding properties and japan drier and he did a french polish type of application with it. I don't remember the proportions.
I've wondered about testing it for guitars, any thoughts?

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Jim Watts
http://jameswattsguitars.com

Jim,
I've got the same article, and I'm thinking of trying it on a little soprano uke I'm throwing together. I want to use the Pratt & Lambert Flat instead of the gloss as I think it will be more forgiving of any mistakes. I'll let you know how it turns out. I have used that formula with some behlens rock hard varnish on a custom mallet, and it seemed to work well. It took about 3 days to get really hard.

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Tracy
http://www.luthiersuppliers.com

Saw a lovely finish of shellac, tru-oil, shellac, tru-oil then buffed I think it was 8 layers 4 of each

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Formerly JJH

I learn more from my mistakes than my successes

Tracy,
I'd love to know how it comes out. Please keep us posted.

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Jim Watts
http://jameswattsguitars.com

Colin, Michael,

I have read that one of the advantages of shellac was that you don't have to care too much about dust . Does the same apply to Tru-oil?

Thank you
Antonio

"shellac" I mean french polishing

You mean dust during application?
First, any contaminate in the film is contaminate in the film no matter what the media is. If dust gets in a sprayed stream or wet film the worst that can happen is it becomes entrapped particles. Dust particles on the muneca, in the shellac or on the surface of the guitar or film during application can become scratches at worst and entrapped particles at best.

So my answer is this is a falsie, Where did you hear this by the way?

Antonio, Tru-Oil, like oil varnishes (which technically it isn't, but in practice is…) takes a fair amount of time to cure. So yes, dust is more of an issue than with lacquer or shellac, both of which dry almost instantly.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

My question is this I guess, then: How do you avoid witness lines? If I final sanded with 400, 600, 800, etc. and then on to buffing there would be little witness areas everywhere. I have been using a french polished top coat which hides the witness lines and makes it very pretty but I would like to trim some time and labor off if possible. I know it can be done but I don't want to have to redo a commission after 6 weeks of hard work. I intend to use Behlen's Rockhard varnish.

I have this ideal dream of shellac sealer coats with pore filling done with pad and pumice, which is in my comfort zone, and then a top layer of oil varnish however it must be done. The most beautiful oil varnish finish I have seen yet was on a Tom Ellis mandolin. It was magnificent!

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"We might not be big but we sure are slow"

i love oil finishes and i use micro mesh to burnish the wood first then apply the oil and cut back between coats (3,600 grit) till you get to about 7-8 coats then then matt it down with 2,800, Add another coat and polish up from 2,800 all the way to 12,000 grit.
then you can buff up with swirl remover and 12,000 grit micro mesh but you probably wont need it.
let to dry for at least two weeks.
even tru oil takes at least this long harden properly in my experience then buff out to high sheen with a very very very light coat of furniture wax polish (not on the top) make sure the wax has hardend buff out some more and you have the glossiest oil finish you can get.

its also good to raise the grain three times whilst on the wood prep stage.
the most important factor of an oil finish is surfice prep you must sand as fine as you can go and you will get wonderfull results with micro mesh (i use micro mesh mx for metal up to 500 grit and then go right down to 6-8,000 on the raw wood)
it also helps to fill the grain with epoxy like you would with any finish.

you dont get any whitness lines with this method

thats how i do it but i know other people have good results with the other methods.

joel.

I have found that if applied properly, by which I mean lightly enough (when you wipe it on you almost wipe it all off again) one half of the back is dry before you have finished the other half. So it almost dries as you apply it. I have never found any problem with contaminate dust if the usual precautions are taken in the finishing room. Unlike of course the brushing oil varnishes as used on violins etc, where they can take a week for one layer to dry.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Laurent, what kind of oil varnish have you sprayed? Any problems with "runs"? Also, no witness lines?

thanks.
SR

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"We might not be big but we sure are slow"

Thank you for your answers




I heard this on a youtube video.... "Shellac dries almost instantaneously so you don't have to worry to much with dust in the air. You don't need a dust free environment."...

Colin , the way you described it gives me some hope

Anyway can someone please post a link to read some information about "the usual precautions in the finishing room" - I am a beginner, I have to do everything in the same room.

Antonio, just keep the room dry, warm, draught and most importantly dust free.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Behlen Rockhard.
Runs happen when spraying too much and/or too thin, you have to find out what works with your setup, room temp etc.

I spray the varnish as it comes out of the can, more or less, and add turpentine (or naphtha which evaporates faster) to regain the original fluidity.
Varnish tends to gather at the edges at it levels itself out, spraying just the "right" amount is no different than with lacquer or shellac.

To minimize witness lines I add a capful of acetone to the varnish cup in the gun, more or less. Acetone will somewhat accelerate curing.
Witness lines disappear with the next coat so I'm not worried about them before the last coat. I scuff sand the first few coats without being fussy about leveling, marroon scotch brite pads work well. After about the 4th coat I completely level the finish with 320grit open coat paper (without sanding through), spray the next coat, wet sand with P600, spray again, wet sand with P800, repeat until I reach P1500 before the last coat. The last coat is sprayed as thick as I dare without sags and I usually do the final leveling with P2000 and P3000 without sanding through the preceding coat, then to the buffing wheel with Menzerna fine and super-fine.

This is a very forgiving finish, again it really levels itself out because it takes so long to cure (at least 4 hours). And because of this the only issue is dust (and bugs…), I find it impossible in my environment to avoid small, tiny dust specks on the surface.
If you environment is 99% dust free it is possible to recoat when the preceding coat is still tacky without scuff sanding. I'm imagining that it would go a long way to eliminate the witness lines issue.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/