Spirit off and french polish [Pictures] - created 01-28-2008

schiaffella, enrico - 01/28/2008.08:28:00

Hello, I see that Milburn advices to spirit off the guitar after each session. The purpose is removing excess oil. I don't really understand why this is done after each step, since when you recharge the muneca, you need to add oil again in order for the muneca to slide properly. Could'nt one just not remove oil from previous session and use that for next sessions?

I don't bother spiriting off. I use mineral oil for the lubricant. My personal theory is that it evaporates away eventually and disappears from the surface.

The operation smooths the surface, (takes out little lines from the fabric of the pad) and helps harden it. So I find that with the way I do french polishing, it does just that for me.

Before stopping a FP session, I let my pad get pretty dry. This leaves very few lines or high spots.

I don't worry about getting rid of any lines until I am ready to completely stop FP. (I hesitated to use the word "finish".) If I have a large blob, I will sand this down, but I hold off most of the leveling until late in the process.

Enrico,

Milburn recommends doing both. At the end of each session they describe letting the pad be very dry for 'stiffing.' which sounds like what you are talking about. But also after the guitar rests for an hour or so they do the passes with the alcohol only, which they call 'spiriting off.' This is supposed to let any oil that is not going to be incorporated into the finish have time to - I guess the word is precipitate - and the alcohol clears it away.

That "spiriting off" looks like good practice..except if you put too much alcohol in your "spiriting off" pad. I had some little temporary disasters in that vein. I do not see it as compulsory if you exhaust well your pad but the beauty of shellac is that you can find several ways to work with it. The Milburn tutorial is a very good text, I should read it again.

Enrico, you may be skeptical that the spiriting off is not necessary or that it might damage (remove) the finish. I know I was. Give it a try and you will find that it really does help. It burnishes down the finish and it removes oil

without

removing the finish.

It does help to have experience to know how dry the pad should be, but I follow the same procedure as Alain - I have a "starter board" that I put the pad on first to make sure it is not too wet.

Too-wet kills.

There is always some shellac left in the muneca after each session, and it becomes too condensed rather than solute and fluid. I think just alcohol makes the shellac easier to leave the muneca/clothe and being attracted by the surface. As for the idea of removing excessive oil, I'm not quite buying it.

I think cured shellac can withstand more alcohol than you might expect. Waiting an hour before spiriting off lets that finish partially cure and a straightline swipe with alcohol isn't going to ruin it.

I'm not that experenced at FP but using Naphtha (coleman fuel) to remove the oil is safer according to my finishing books as well as other sites I have read on the internet.

I've done that as well (used naphtha), and it removes the oil just fine, but it does not burnish the surface and help build a shine.

Seriously, give it a shot and see if you don't like how it works.

I agree with Chuck on this. It made a lot of difference for me.

but it does not burnish the surface and help build a shine

That's what modern fine grit sandpapers and buffers and compounds are for.

That's right, but if you are into traditional french polish, you don't use anything but that to get the shine and the final finish.

But, I wasn't ever too good at it, and after I got enough finish on the instrument I had the best luck with a fine wetsanding and then buffing.

Sure, but to what degree of traditional do we strive for? I mean, do we pull the main breaker out and do it by candlelight also?

I had become pretty good at spiriting off, but one day I was cleaning up my first mandolin(completely French polished, including the traditional spiriting off deal) and used Meguiar's #9 or #7 because I had just cleaned up a very grungy old guitar with it and I had both the compound and rag right there. Well! That French polish job took on a whole new dimension right there. I've never looked back...

We don't have to go to fine grits and power buffers, as it will polish to a lacquer like(and then some!) gloss by hand with Meguiar's #9 and #7, but the big buffer rules in the speed dept. We can "spirit off" with naphtha to rid the oil, and hand buff with liquid compounds.

It's not a sin....

Sounds good. It just depends on the builder and if you are hung up on making suere you do things the "old school" way or not, some folks like that.

But like we said before, spiriting off does more than just remove the oil. If I don't spirit off, I end up with an un-even surface with lines and marks left by the pad. I can burnish and smooth them by spiriting off, OR I can do the same thing by letting things sit for a few days and wetsanding and polishing.

Yeah, I've never let something like traditions get in my way . If something is traditional and still holds up, sure, I'm all for it, but this is a process that developed before abrasives existed. I can think of no reasonable reason to not use abrasives. From day one, I've used sandpaper between bodying sessions to smooth over the bumps and ridges. 150 grit, BTW. Nobody believed me then, either By the last session(3-5 of them),, she's good 'n smooth!

Sanding and buffing are a waste of time!

Does this hold up? It is straight off the pad - no sanding, no buffing. Do you believe me?

And another.

Not saying it couldn't be done, but rather, there are other ways... perhaps even better.

Aww, Chuck- who are you kiddin'- that looks just terrible.

No, just fooling! That looks great, you are very good at french polishing! I don't have it down that good.

I can't claim that I know how to finish with fancy spray gear and big buffs. I don't have that stuff (nor do I have the space!).

My point is that if you use the "processes" of the French polish method effectively, it is easy (and FAST!) to develop a robust film with good shine.

Enrico, I see from your recently completed guitar that you are a successful French polisher. It is a beautiful instrument with a great finish. Did you end up "spiriting off"?

Give it to them Chuck!! (I agree with you entirely.)

Chuck I envy your FP skill!

You are being too kind Chih-Wei, the finish on your instruments is superb. But thank you all the same.

I don't make enough instruments to get the required practice, but I do buy wood every now and again. I usually scrape down a section of new wood that I've acquired and FP a patch to see its true character. I get time behind the pad, and most of my rough lumber has a shiny patch somewhere on it.

If you want a super glossy look, you can "spirit off" at the very end with a light dilution of styrax benzoin ( benjamin??), as did cabinet makers in the old days. Disadvantage is that you loose some hardness. Bonus: very nice smell too.My first Maestro did that, I do not, I prefer

a more natural look.