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I would appreciate the sharing of a varnish under French polish or even just varnish finish schedules. Would someone share there secrets with me?

Thanks

Tim

Alan Carruth has posted his Behlen's Rock Hard table top varnish schedule here previously.
I can personally recommend his method - as it does work quite well for me.

Thanks

There's 3 threads(part 1 part 2 and part 3) on my varnishing process and schedule in the tutorial section. Here's a link to part 1.
http://www.luthiersforum.com/forum/viewtopic.php?f=10117&t=33117

The oil based varnish I use is more durable than french polish. I don't know why you'd want to french polish over it.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

FP over oil varnish was the finish on Gibson instruments (incl. mandolins) at the turn of the century before they switched to lacquer. There is no secret, spray or brush your oil varnish, scuff between each coat and spray again, scuff/level, spray etc. until you have a perfect surface, then FP it. Witness lines do not matter as FP over the varnish will make them invisible.

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

Laurent is correct about this being the finish of choice for Gibson back in day, and some of their most desirable instruments, including the "Loar period" mandolins of the early '20's, have this finish. This is probably the main reason why many of today's top mandolin builders do it this way, so head on over to Mandolin Cafe and read all about it in one of the numerous threads about it over there. I can add that I've used it in mandolins, pretty much as Laurent describes it, and it works as advertised as far as masking witness lines. I have also used Tru-oil over varnish (Epifanes), which has a similar effect, and I like that even better.

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Rian Gitar og Mandolin

I believe FP was used to get a quick gloss and hide witness lines, which are unavoidable with oil varnish unless acetone is used in the mix, and a mechanical buffer used for the final polish.

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

Interesting.
I guess this method would save time, no?
Also saves a lot of elbow grease?
How long would one let the varnish dry?

Does this amount to filling with varnish and then a normal shellac French polish?

Hupaand asked:
"Does this amount to filling with varnish and then a normal shellac French polish?"

Pretty much.

There are a couple of advantages to doing it this way, and (of course) a few disadvantges. The big advantage is that, since the varnish builds pretty fast, and you don't have to sit there rubbing away for so many hours, it's a big time saver. Once you get a pretty much level surface, you can switch over to FP and get it out the door. As Laurent says, it's also a great way to mask witness lines. My experience with the 'Rockhard' varnish is that they will be considerably reduced if you can wait a month before doing your final polishing, but you may not want to wait.

The disadvantages are that most oil varnishes do shrink a lot over the first three months or so: A level coat on oak or padauk now won't be nearly as level in a couple of months. If 'level=good' in your lexicon, the varnish won't save you much in the way of lead time. Another disadvantage is that oil varnishes, in general, have the 'right' refractive index, which gives them a 'deeper' look on wood than most other finishes have. Putting another finish over (or under) the oil varnish will tend to a more 'veiled' look. Finally, FP does tend to wear a bit quicker than oil varnish, which is tougher than shellac, even if it's not as hard. That thin coating of FP can start looking pretty spotty in a few months.

Thanks, Alan.
I've got a couple of builds with several coats of varnish,
that have been sitting around since May.
I'm going to try it out on one and see.

One other thing I should probably mention is the old painter's 'fat over lean' rule: never put a hard layer over a soft one. The soft layer will move, and the hard layer can't move with it, so it cracks. For artists, that usually means to use less oil and more resin in the under layers, and gradually increase the oil content of the medium.

No oil is needed in shellac, of course, and, from my experience, adding it can (can!) lead to problems with shrinkage, checking and darkening. However, because of the way the bugs produce it, shellac is much less brittle than most 'pure' resins so it's unlikely to cause checking when used properly with the right varnish. I would not put it over a 'spar' varnish; those tend to have a lot of oil content, and to be soft. Most instrumentmakers these days use a harder 'rubbing' varnish.

You also have to remember that one of the classic furniture makers antiquing methods is to put a layer of shellac over tacky varnish: in that case the shellac will certainly dry faster and harder, and will cause checking. This is not something any of us would be likely to do, but still...

You don't want to do that. Proper pore filling and sealing is needed. Most varnishes have a rather amber colour, and pretty dark for Rockhard. You don't want to spray gallons of the stuff, and level it between each coat, to fill and seal the grain. It is discouragingly easy to get splotchy results on clear woods (spruce, maple, myrtle etc.) where you have dark and lighter areas. Softwoods, especially, needs to be sealed pretty well. This can be done with a thin varnish of course, but then it needs to be sanded down to bare wood in order to have a clean canvas to evenly spray the dark varnish, so to speak.

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

Will this work

1 Wash coat shellac for sealing

2 Pour fill grain

3 BRUSH varnish "rock hard" let set for 2 months?

4 FP over varnish.

Of course level sanding between all coats

I have basement shop need people friendly finish do not wish to spray.

A Laurent says, there are much better fillers than oil varnish. I have often used a French polish type of pumice fill under varnish, and it works fine so long as you sand right back to the wood (leaving the filler in the pores, of course). It will save a lot of lead time, and shring back much less than the equivalent amount of varnish.

You _could_ wait two munths after applying the varnish, of course. Whether you _need_ to depends on how level you need the finish to be. I, personally, prefer wood that looks like wood: if it's open grained I like to see at least some evidence of pores, so a bit of shrinkage doesn't bother me in the least. The current standard in the guitar world is wood that looks like plastic, with an absolutely level and smooth surface. This is, of course, a 'production' look, but it's the factories that set the standards that most customers accept. For that look a two-month wait might not be enough, especially if you're using the varnish as a filler.

You want to sand back to the wood after pore filling, thus you need to seal again with shellac. I wouldn't do a "wash coat", but spray a generous 3 or 4 coats, pore fill, sand back to the wood, spray another 3 of 4 coats, level everything with 400grit, then start with the varnish schedule.
There are 2 reasons for this: if you have maple purfs and use a tinted porefill you really want to seal the maple (and the top by the same token) against the porefill. Maple does have pores and when tinted pore filler gets in there it can become utterly depressing to be a guitar builder. Then oil varnish cures poorly, if at all, on oily woods like rosewoods, some ebonies and the like. It is possible to seal those woods with a thinned oil varnish (at least 1:1) with the wipe on/ wipe off approach, repeat until sealed, then start building with a progressively thicker varnish mix, but that takes patience. De-waxed shellac is much more effective.
One thing to keep in mind is that the longer the varnish cures, the harder it is to level and make sanding scratches disappear.

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

Hey Arnt, do you care to expand on this, perhaps with pics!?

Okay, I'm giving this a whirl.
I pore filled the mahog with paste filler,
sprayed 6? coats of Sher Will fast dry varnish back in May.
Had to move, and too much work, so the varnish has really cured for a while.
I got some med amber flakes from LMI,
and wet sanded the varnish coats with 600.
Tomorrow I plan on laying the fp on.
Prototype git, weird hybrid finish.
I'll let ya know!
Hey, Alan, all the research I've done on fp says to use oil, no?

The classic French furniture maker's method of FP floods the bare wood surface with oil, wipes back, and applies the shellac over that with the pad. Some of the oil is drawn to the surface by the alcohol, and lubricates the pad. You can, of course, do the pumice fill in this system on open grained wood (or even on close grained wood!). This looks nice, because of the oil on the surface, and builds fast. There is some evidence that the early violin makers may have used this system from time to time for the 'ground' coat, although, as with everything having to do with painting fiddles, there's controversy about it.

I have not tried the Millburn's method of mixing the oil with the shellac.

In my own experience, I think it's better to minimize the amount of oil in the finish. I've had issues wih 'witness lines' when I needed to touch up older FP finishes where I used oil, checking issues, and darkening, when I've used a lot of oil. I'm also loath to add much oil to a guitar's finish, simply because it adds damping, but that may be an absurd prejudice.

There are lots of ways to FP, and they all work for somebody. Find the one that works for you.

Okay, I did my first 2 sessions, and I like the french polish.
It's easier than I thought.
Seems the big trick is knowing how much of what to put on the muneca.
Something that can only come with experience.
Next acoustic will be total fp.
I like it!
So far.....

Update.
The 2 guitars I'm doing are 2 different varnishes.
One is Old Masters, the other is SW fast dry.
4th coat on the fast dry isn't working.
I'll have to sand back to varnish, and keep going with that.
The O.M. varnish is going perfectly,
so far...
Just thought I'd let ya know.