Official Luthiers Forum!

Hi,
I was browsing the web the other day and I came across a luthiers web site
where one of their finishing options was French Polish with a coat of Tru or
Danish Oil over it.
Has anyone tried this?
It seems like it might make the finish more water resistant?
Does this sound worth doing or not necessary?


Thanks

Will not make Shellac any more water resistant FP'd shellac has no cold water resistance issue anyway warm water may blush it but I do not believe the Danish oil or Tru oil will help any. Plus I believe the you would be ruining a classic finish and making it harder to do repair work to later down the road.

Tru-oil is a penetrating oil. A slow drying oil with light weight resins that penetrate the wood. placed over shellac doubt it would adhere very well. Danish oil I am not as familiar with but suspect the same issues though I do think its more of a true rubbing varnish.

I've done thin coats of Tru-oil over a French Polish many times and it adheres just fine. I don't do it for waterproofing but use it as I believe (maybe wrongly) that it is a little tougher than FP on it's own. It's not as tough as nitro or other modern finishes though.

I think the notion of True oil as a "deeply" penetrating oil is way overdone. Shellac penetrates as well - at least that's what I find when I sand off seal coats after routing bindings etc. It doesn't go in very deep - about the same as Tru-oil. Maybe in 20 years the Tru-oil will sink in further than shellac - I hope I live long enough to complete a trial - but I have guitars over 3 years old that have had Tru-oil tops (with no FP undercoat) and the tone just keeps getting better and better.

If it is your personal guitar and you take good care of it then I would probably stick with FP and wait for it to harden up fully. It is very tough stuff when it does.

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

I use tru-oil over shellac also as my finish on the back and sides. It does dry well over shellac. Actually, it is a problem for it to dry on rosewoods, ebony etc.. without the shellac under it. I agree with Dave that it is a little tougher than french polish initially and I really like that it gives a little alcohol protection also. I prefer to leave the top with just shellac, but a thin coat of tru-oil doesn't seem to hurt the tone at all. I started using this because I really don't want to use anything toxic if I can help it but, like Don always says "someone will spill their beer...". When I have taken my time and really concentrated on a smooth level finish I have been pleased with the sheen of the tru-oil buffed out with medium stew mac compound. I have never tried for the ultra wet gloss look but I have heard it is possible. If you are going to try it I would say make sure your shellac ground is pretty level before you apply the tru oil and then let it dry for longer than when it seems dry before you level sand it. I apply it like french polish, in thin coats with figure eights and then long straight strokes right after. It seems right up there with french polish in terms of repair and shellac sticks to it fine anyway. Please take all this with a grain of salt as I am only 4 guitars into this process and I still change little things here and there but the first one (a year old) looks great still. Umm, at least where it was great to begin with. Hope this helps!

_________________
Burton
http://www.legeytinstruments.com
Brookline, MA.

Thanks evryone for the info, this IS my personal guitar and I will take care of
it . Ill probably stick with FP.
Just wondered.

Tru-Oil is actually a fast-drying surface finish. The "surface" part is what's important for lutherie. Nitro, shellac and "short" varnishes (like Behlen's "Rock Hard" or many of the polyurethanes) are all surface finishes. They dry hard and do not continue to sink into the wood. For an oil finish to meet those requirements, it must be polymerized. That's a heating process that partially cures the oil before it's sold. Tru-Oil is polymerized, and offers very good moisture and solvent protection.

Tru-oil CAN penetrate into the wood if you put it on heavy and leave it on the surface. It's not made to be used that way, though. A wash coat of shellac will also help to keep the oil on the surface while it drys. Check out LMI's tutorial on Tru-Oil application.

Polymerized oils aren't used often outside of lutherie because they're expensive. It'd cost a small fortune to finish furniture with it, for example. However, a little goes a long way, and I've read that you can most likely finish three guitars with one of those little 3-ounce bottles of Tru-Oil.

Tru-Oil is quite easy to use--just wipe it on and wipe it off, and wait 24 hours between coats.

I'll note that using a drying oil, such as linseed or walnut, as the lubricant in French polishing, gives some of the same benefits, and has some of the same drawbacks. It seems to co-polimerize with the shellac, and form a slightly tougher and more solvent resistant finish. However, as with any drying oil or finish that contains it, it will shrink and possibly craze over time, and darken. There's no free lunch.