Starting to Finish No. 1

[Eric Knapp]

Hello, I'm starting the daunting task of finishing my first guitar. I must be a glutton for punishment as I decided to teach myself French polishing with this project. Here is it after 5 sessions.

As you can see in these closeups, I did not do any pore filling. I want the 3D look of the wood grain. I think my general woodworking experience has given me a bias towards that look. I think I'll probably try pore filling on a future guitar to see if I like it.

I'm posting here to get some feedback on French polishing. I'm assuming many of you are quite good at it. How did you learn it? How long did it take before you felt like you were in control of it? I'm trying to learn it by reading and watching videos. I think every post I've read and every video I've watched has a very different approach. I decided to just jump in and make mistakes. I get the basic concept but the technique will take a lot of practice, I'm thinking.

Thanks,

-Eric

[Barry Daniels]

That looks a lot better than my first (and only) attempt at a French polish.

I did use the pumice pore fill technique and that turned out to be one of the easier steps of the process.

[Bryan Bear]

Looks great so far!

Many have trouble accepting the open pore finish on guitars. This particular guitar is well suited for one IMHO. It has a cool vibe that will be complimented nicely with that approach.

I wouldn’t say I am good at FP but it is the finish I use. I think there are as many approaches as there are people doing it. Seek out and read the Milburn tutorial on French polish. That will really help you understand what is happening in the process.

I think, in the end, we all come to our particular approach by doing it and figuring out what works for you. It is kind of like learning to drive a stick shift. People can tell you how the transmission works and how to shift gears. That is important information but it is just the start. You can ride shotgun while someone does it and get a feel for it but that doesn’t tell your body and mind how to coordinate the information. At some point you have to get behind the wheel, kill the engine, bounce the car around a bit, and get lost in the shift linkage occasionally. Eventually you start to do it smoothly in a coordinated way. As soon as you think about it, it gets hard again.

[Eric Knapp]

That looks a lot better than my first (and only) attempt at a French polish.

I did use the pumice pore fill technique and that turned out to be one of the easier steps of the process.

Thanks, Barry. What type of finish do you use now? I like the look and feel of the FP but I am open to other types of finishes.

-Eric

[Eric Knapp]

Looks great so far!

Many have trouble accepting the open pore finish on guitars. This particular guitar is well suited for one IMHO. It has a cool vibe that will be complimented nicely with that approach.

Thanks, Bryan. I know that pore filling is probably needed if I ever plan on selling instruments. This guitar, and all its beginner flaws, is all mine and won't leave the house. I'm doing it how I want to. That may change some day.

I wouldn’t say I am good at FP but it is the finish I use. I think there are as many approaches as there are people doing it. Seek out and read the Milburn tutorial on French polish. That will really help you understand what is happening in the process.

Thanks for the reference, I'll look it up and read it all.

I think, in the end, we all come to our particular approach by doing it and figuring out what works for you. It is kind of like learning to drive a stick shift. People can tell you how the transmission works and how to shift gears. That is important information but it is just the start. You can ride shotgun while someone does it and get a feel for it but that doesn’t tell your body and mind how to coordinate the information. At some point you have to get behind the wheel, kill the engine, bounce the car around a bit, and get lost in the shift linkage occasionally. Eventually you start to do it smoothly in a coordinated way. As soon as you think about it, it gets hard again.

That is a great analogy and Imma gonna steal it. I did learn to drive a stick that way and the guy who "taught" me just had me stop in the middle of a big hill and then said, "Now go." Heh, I was back at the bottom of the hill before I caught on. I think I'm well on my way and I'll post the final results when I'm done.

-Eric

[Alan Carruth]

I think if FP as the 'zen' finish; it's all about being aware of what's going on. You can't make it do anything it doesn't want to do; if you are having problems usually the best thing is to stop, give it time to dry, and pick it up again; maybe after a very light sanding. I've never gotten a FP finish 'perfect', but it seems that you can get halfway from where you are to perfect by simply putting in as much time as you already have invested in total.

At one point I used it on everything, but these days I tend to confine it to the soundboard of spruce top Classicals, where the minimal weight and damping are most beneficial. I used it on the cedar top of a 'show' instrument, and got used to spending several weeks after every show re-doing the top. Finally some kid dug a piece out of it with his fingernails when I wasn't looking, so cedar tops get varnish.

At this point I'm using Murdoch's 'Ure-alkyd 500' floor varnish as my standard finish. It's not perfect, but no finish is. I like the look of it, it's very hard, goes on almost as thin as FP, wears extremely well, and resists sweat and other chemical attacks. The hardness makes it pretty labor intensive to rub out, and it does nor cure reliably on some woods, so it can be tricky.

With any finish you look for something that has the features you need and drawbacks you can live with.

[Bryan Bear]

With any finish you look for something that has the features you need and drawbacks you can live with.

Boy you said it all right there!

I have been using French polished Royal-lac on the last several guitars. I always reel a twinge of reluctance to answer anytime someone asks what it is. I have found that it works for me and my situation in the spirit of Alan's quote above, but never feel like I want to be perceived as recommending it to the person asking. Their situation may be totally different than mine. Likewise, they may have very different requirements of their finishes. As it stands for me now, all of my guitars go to people who I can have the conversation with about FP not being treated like the factory finishes at guitar center. If I were hanging instruments in a shop for strangers to buy, I would have to rethink my approach.

[Eric Knapp]

I think if FP as the 'zen' finish; it's all about being aware of what's going on. You can't make it do anything it doesn't want to do; if you are having problems usually the best thing is to stop, give it time to dry, and pick it up again; maybe after a very light sanding. I've never gotten a FP finish 'perfect', but it seems that you can get halfway from where you are to perfect by simply putting in as much time as you already have invested in total.
...

Thanks, Alan, this is a good perspective. When I make things for others I use a finish that's appropriate for the use and intended user. I made a rocking horse for a toddler and used General Finishes High Performance finish. I expect that the first several guitars will be for me and my daughter so I will try and get better at FP. Perfect is not my goal, so this seems like a good fit.

-Eric

[Eric Knapp]

...
I have been using French polished Royal-lac on the last several guitars.
...

I was going to ask if you could use FP with Royal-lac. That should raise the durability a bit. I've heard from other woodworkers that it works and feels just like plain shellac. I have a pound of shellac flakes to use up first and then I think I'll try Royal-lac.

-Eric

[Bryan Bear]

Yes, you can FP with Royal-lac. I have found it works a little bit differently but exactly what that means is hard to describe. It seems to like a bit more oil than regular shellac and you can adjust the rest of the parameters as you work.

I have talked with a few other people who FP with it over on the OLF. They seem to agree that it wants a little more oil. Not a ton though. It is with it to me for the extra quirks in exchange for water and alcohol resistance.

[Marshall Dixon]

...How did you learn it? How long did it take before you felt like you were in control of it?

Back around 1978 I subscribed to Fine Woodworking magazine and their expert finishing columnist was George Frank who was trained in the finishing business in the apprentice system; informative and entertaining at the same time. He later wrote a book on finishing which is in my local library. His method calls for the application of mineral oil in the early stages, as I recall after sealing with a thin shellac mix and before the pumice fill. I tried that and whole heartedly don't recommend the oil.

At about the same time I bought "The French Polisher's Handbook" (or "Manual" , I can't remember which and both titles are still available) which I seem to recall was published in the 1700's but on the internet I now see references say early 1900's. As I recall it was a thorough treatment of the subject. Clear and concise with a few drawings.

That's all I had to go on and my first project, a walnut burl lamp stand, came out really well. But it is too delicate for the stuff I was doing; dining tables, dressers and the like and didn't use it again until I started building classical guitars. Incidentally, I cut up that lamp stand after 20 years to use for peghead veneer and the shellac seemed hard as a rock.

That guitar is looking fine and you probably don't need to read any more. The old book is interesting though. The one thing that is stressed is to use a minimal amount of shellac when "polishing" even in the early build stages, and let it dry before another coat. That's where my impatience shows.

I have a nice HVLP spray gun and use an acrylic lacquer for the sides back and neck, but my shop is small and dusty and it's difficult to maneuver. French polishing is minimalist and can be done on the kitchen table.

[Alan Carruth]

I've had good luck with flooding the bare wood surface with a drying oil, and then rubbing off as much of it as possible before starting in on the shellac. There is some evidence the the old master violin makers may have done something like this. The drying oil (linseed or walnut) mostly seems to float to the top, but some if it may react with the shellac as well. It gives a deeper 'light' to the finish because the refractive index of the oil matches the wood more closely. I don't use this on guitars because of the added damping of the oil, but as a 'ground' coat on violins the oil followed by shellac and pumice fill goes fast and does a good job.

[Bryan Bear]

Alan, do you do that on the spruce too?

[Alan Carruth]

Bryan Bear asked:
"Alan, do you do that on the spruce too?"

Yes. The object as I see it with the ground coat on a violin is to seal end grain so that the colored varnish doesn't sink in. If this happens you an get a dark spot. There is lots of end grain exposure on the carved top of a fiddle, and, of course, even more on the curly maple of the B&S. I'm justifying the technique based on an article by Barlow and Woodhouse in the CAS 'Journal', Vol.1, #4, (Series 2), November '89, pp 2-9. In the article they used a Scanning Electron microscope to look at small chips from old master violins that had finish on them. They were able to look at the various layers of finish. In general (but not always) there was a ground coat on the wood that consisted of microscopic 'rocks' held together by some sort of binder, sometimes with signs of a drying oil in the wood itself. They were able to make use of the X-ray emissions from the electron beam to determine some of the elements in the 'rocks', and found that to be quite variable, suggesting that the makers used whatever sort of pumice they had in hand, rather than, say, Pozzolana ash. The emissions technique doesn't pick up anything with an atomic weight lower than silicon, so they could not look at the composition of the binder. At the end of the article they solicited samples of wood from makers who thought they had the 'secret', and were able to look at a number of those later, as was reported by one of the authors on a violin makers e-mail list. There were two sorts that matched in appearance and composition; a standard French polish fill, and 'Rubio Rubble'. Both of these would have been within the technical ability of a violin maker, and the needed materials were available.

FP fill needs no introduction here. Rubio rubble was devised by luthier David Rubio based on his knowledge of chemistry and the history of finishes. It's based on the production of 'lakes' pigments; a method of 'fixing' organic dyes to render them color fast. If one mixes a solution of alum with one of lye insoluble aluminum oxide particles precipitate out. These are transparent when pure, but can incorporate molecules of dye if there is any in the component solutions, yielding a transparent color fast pigment. The most common lakes pigments are made from extracts of madder root, to produce shades of orange, red, and purple. Rubio applied one solution (the alum, if memory serves) to the wood and allowed it to dry. Applying the lye to that causes the formation of aluminum oxide in the wood surface as a milky or 'frosted' coating. This is then saturated with Venice Turpentine, a thick oily fraction distilled from larch resin (again relying on memory) that has the property of wetting well. This renders the oxide layer transparent, and then hardens to a binder.

Both of these coatings fit the characteristics of the old master ground coat, and used available materials and known methods. I went with the FP fill simply because I knew how to do that, and find that it works well.