Types of Finish: Compare & Contrast, Pros & Cons [Archive]

sunburst

Nov-17-2010, 12:15am

If you hand me a mandolin with a well applied, quality finish, I'll probably have to ask you what it is, if I want to know. That's how similar they are in appearance.

Here are a few specifics:

Nitrocellulose lacquer

Can be buffed to a high gloss that is hard to rival. Very clear, reasonably protective, not too difficult to apply and very forgiving of less-than-great application, it just takes more work to get it looking right. Repairable to one degree or another, more so the newer it is.

Waterborne lacquer

Less toxic than many other finishes, safer to apply and require far less safety equipment that many other finishes. Nearly colorless, though some tend to a blueish color, so amber is ofter added to counteract the blue. Fast curing and good gloss.

Oil Varnish

Slow to cure, some slower than others, can be nearly colorless or more amber colored. It takes a lot of work and time to apply, brushing requires skill, spraying requires skill. It takes a long time for oil varnish to cure enough to buff to a good quality high gloss.

French Polish over Oil Varnish

Oil varnish is described above. FP over oil varnish is mostly a way to get a good high gloss with less waiting. If the shellac FP is not kept very thin, crazing is likely.

Spirit Varnish

This is shellac with additives. It can be nearly completely non toxic, depending on additives and the kind of alcohol used, it can be applied by brush, spray or french polish. It damages pretty easily, especially when it is new, but it repairs well.

Ed Goist

Nov-17-2010, 1:37am

I think the answer depends on what pro/con factors you are looking at. Repairability? Durability? Gloss factor? Ease of application? Tone differences? Historical consideration? Toxicity? Clean up? They've all got their pros and cons, so context of what you are looking for will help direct the question a bit better since there is a lot to say about each of them...

Hi Geoff:
I'm looking at this question only from the perspective of a mandolin owner/buyer.
Hence, I'd love to know how the various finishes might affect (if at all) a mandolin's tone, appearance, durability, repairability, price, and resale value.

Ivan Kelsall

Nov-17-2010, 4:42am

I can only comment on my 2 instruments - my Weber "Fern" is has a 'laquer' finish & my Lebeda "Special" has a Varnish finish. Tonally they are different,as one would expect,but not because of the finishing method.
For me,the big benefit of the Varnish finish on my Lebeda,is the ease with which it comes clean of finger / wrist marks - they can be almost blown away. My Weber on the other hand, almost requires a steam cleaner to get the marks off.
I suppose that as usual,our personal preferences determine what we'd go for re.any specific finish. Ultimately,regardless of finish type,it's what the instrument sounds like to us as individuals - no secret there !,
Ivan

grassrootphilosopher

Nov-17-2010, 5:52am

I do think that the type of finish is the very minor fact that determines value and sound.

As sunburst said (and I don´t try to talk anyone into believing that I have any indepth knowledge about finish types) the appearance can be pretty similar. Laquer I found to look glossier than varnish whereas varnish rubs thin. I´ve got a varnish mandolin for 4 years now and the neck is slowly loosing its finish (well the finish is dulling). You could call the process speed necking by use. I pretty much play the instrument daily. I would not expect this to happen so quickly on a laquered instrument. Does it matter to me? No. Varnish tarnishes more easily. If you have a hard hand etc. you´ll wear through varnish easier than through laquer. On laquer you´ll see the scratches etc. Laquer gets crazed etc.

If I were in a buying mood - and I think you are, Ed - I´d focus on the built the most. Is it an oval or an f-hole mandolin, which should be the top wood (Sitka - warm but possibly muffled, Carpathian - warm and musical, Adirondack - powerfull yet possibly strident with possibly the longest break in time), coupled with the question of tone bars vs. x-bracing (tonebars seem to be the way to go these days with even builders like Gilchrist and Duff while a good x-braced mandolin gives the reward of a faster break-in period - the combination bracing and top wood seems to determine the sound of the instrument), the back wood (hard rock maple vs. sugar maple). If everything is decided upon then comes the question of the finish (to me). Next you´d have to ask yourself which builder is able to build your idea of a mandolin. And can you single out a builder that you can afford.

As an afterthought and unrelated to your initial question: The varnished Fern that was/is on the classifieds is a fine proof that through the classified system you could get a good used instrument that needn´t cost an arm and a leg.

Brent Hutto

Nov-17-2010, 6:41am

I strongly prefer durability as an attribute of an instrument finish because I believe when properly (thinly) applied almost any of the common finishes can get within spitting distance of the same sound quality. Not saying that there can't still be differences that really experienced ears detect but the effects are subtle. The exception being heavy finishes which are bad per se.

That said, as I've bought better and better quality instruments (guitars and mandolins) the finishes have gone from catalyzed lacquers to nitrocellulose with the next stop being french polish. I've just accepted that there's a tendency for fine instruments to use the less durable finishes because those finishes are desirable among most folks who build and buy good guitars and mandolins.

I take pretty good care of all my instruments but refuse to treat them with kid gloves. Reasonable precautions like washing my hands before playing, wiping them off with a clean cloth after playing, storing them properly and not banging them into belt buckles? Sure. But I don't cry over dings and I don't mind having my friends play them and I've learned to ignore the fact that nitro finishes will get cloudy where my arm rests on them and that minor contacts that would be shrugged off by a more durable finish will leave traces that won't wipe off on a softer finish.

So my advice is there's nothing wrong with deciding what finish(es) you prefer but in the end don't let it influence your choices in mandolins. At the level you're shopping, Ed, all the finishes are going to be thin amd well applied. So pick the instrument that floats your boat and whatever finish it happens to have will become your new favorite finish.

Big Joe

Nov-17-2010, 7:58am

If you want ultimate durability then poly is pretty hard to beat. It is not as easy to fix if you do get a problem, but it is very hard and durable and can look as if the instrument is dipped in plastic with its shine...oh wait... it kind of is :) . We used some water based lacquer years ago that dried hard as a rock and crystal clear. The only problem is that it is very hard to work on once it is fully cured. I have one now that we need to refinish and the only way we have been able to get the old finish off is to just sand it away. That is my least favorite way to remove finish. It is slow, and lots of work.

There is a tonal difference in the various finishes. It is only one amongst many issues in the chain, but it certainly does make a difference. There is also a difference in the way the pick responds to the instrument. On some finishes it is actually something you can feel in both the left and right hand as you play.

Everyone has a preference based upon their experience, ear, pocketbook, or ???. My personal preference is for a good varnish finish. It has the tone and response I like best. Roland White did not want varnish on his mandolin when we built that. He requested what is essentially a Master Model but with a nitro cellulose lacquer finish. His mandolins sounds incredible and play wonderful. Again, everyone has a preference.

I have found once you find what you like it is hard to switch to something else and be as excited as you may be. It is not a matter of quality of the instrument, but just what you get used to tonally and in the response of the pick on the strings. In any case, just about anything you put on your mandolin can give protection from the elements... some better than others... but some finishes are maybe just not the best choice for ultimate tone and playability. That is one reason many pay quite a bit more for instruments that have some of the more difficult and fragile finishes.

What is best for you? That depends upon what you are looking for and what you want to do with the instrument and the environment you will have it exposed to.

Rolfe

Nov-17-2010, 8:40am

The blue appearance in some waterborne finishes comes from the addition of acrylic to the mix. The waterbornes that do not use acrylic have more of the amber tone. The amber comes from the resins involved not from an amber additive. Most luthiers who use waterborne finishes are not using a waterborne lacquer but a waterborne polyurethane, which is closer to the varnish family. I like it for its safety, durability, and appearance (using one without acrylic, that is). It cures hard but flexible. There are very, very few people who have the astute hearing to notice differences in tone among the various finishes.

sunburst

Nov-17-2010, 9:17am

Hi Geoff:
...I'd love to know how the various finishes might affect (if at all) a mandolin's tone, appearance, durability, repairability, price, and resale value.

Tone-
As I said, if you hand me a mandolin with a well applied, quality finish, I'll probably have to ask you what the finish is, and that applies to how the mandolin sounds too. The thinness and quality of application are the things that might affect 'tone', but it really takes a thick, heavy finish film to start to noticeably degrade the sound of a good instrument.

Appearance-
It all comes down to the application. No substitute for skill.

Durability-
Catalyzed poly at the top of the list, waterborne, nitro and oil varnish in the middle, spirit varnish and FP toward the low end.

Repairability-
Spirit varnish and FP at the top, nitro lacquer a little less, oil varnish near the bottom, waterbornes and catalyzed are more replaceable than repairable.

Price-
Depends on the maker. Many have a substantial up-charge for varnish, either spirit or oil, over lacquer.

Resale value-
Hard to say. Perhaps a varnish finish will sell for more used than a comparable lacquered mandolin, but... maybe not.

Lefty Luthier

Nov-17-2010, 9:31am

I think John has summed up the points very accurately. I am no fan of oil varnish for the simple reason that it takes so long to cure but it is beautiful when properly applied. I never use the poly finishes because I have found them nearly impossible to properly repair. My first choice is nitro followed by spirit varnish applied in the French polish fashion.

Bill Snyder

Nov-17-2010, 9:44am

Ed Goist

Nov-17-2010, 10:28am

Ed you have just recently ordered a two point, correct? Looking at Jason's website he states that his instruments are finished with "all natural resin varnishes." I would suggest that you let him use what he is comfortable and experienced in using.

Hi Bill: I agree completely. I'm very much in the school of leaving key aspects of the build to the builder. I figure my heavy lifting as a buyer is done on the front end, researching and selecting the builder.

Hence, I've started this thread more in the hope of becoming more educated about finishes, so I'll have some reasonable knowledge on the subject should the builder (Jason in this case) ask for my input.

Thanks to all for the thorough and well articulated replies here. This is exactly what I was looking for.

sunburst

Nov-17-2010, 11:35am

Thanks to all for the thorough and well articulated replies here...

This is far from thorough info here, only the very basics. Entire text books can and have been written about finishes. A lot has been left out here. Personally, I'm no finish expert, I only know what I've learned working with and reading about various finishes. You can really go in depth studying finishes, but you can get all the knowledge I (and many other luthiers) have and quite a bit more by reading Bob Flexner's Understanding Wood Finishing. It's one of those books that contains and conveys so much information that you feel like an expert after reading it, until you realize that's just the stuff he wrote down, how much more must he know(?)!

Avi Ziv

Nov-17-2010, 12:02pm

French Polish over Oil Varnish

Oil varnish is described above. FP over oil varnish is mostly a way to get a good high gloss with less waiting.

John - would you mind expanding on this a little more? Are you talking about shellac FP over an oil varnish? If so - can you not get as good a gloss with the oil varnish alone? Why would adding the FP reduce the wait time for the under-layer of oil varnish to cure?

Thanks

sunburst

Nov-17-2010, 1:08pm

You can get a great gloss with an oil varnish alone.
These are generalizations here, because there are very many different oil varnishes, but commercial oil varnishes take a long time to cure. The molecules must polymerize, there's a lot more to it than simply drying, and the process can take months or even longer for a full cure. The piece can be put into service much earlier though, because the finish is cured enough for use. The varnish will not buff to a high gloss early because it is too soft. Later, a gloss can be attained but sometimes there can be "witness lines". Witness lines show when one coat is sanded through into the underlying coat (something that happens all the time when a finish is level sanded) in a finish like oil varnish where the coats do not "bite back" into the underlying coats. With lacquer, by contrast, the solvents in each successive coat redissolve all the underlying coats so we don't see witness lines when finish sanding and buffing.
Eventually, after several months of cure, many oil varnishes can be buffed to a high gloss without witness lines and all is well, but the several month wait time is not practical for a production instrument, so it is easier and faster to apply a thin finish of something fast-curing over the varnish and use it for gloss rather than waiting for the varnish.
That is how the Loars were finished, according to most folks who have studied them and their finishes, and they were production instruments so that is the most likely reason for the FP over oil varnish.
Varnish is what they could get easily, so it's what they used. The varnish was slow to cure and they needed a gloss fast for production reasons, so they applied a gloss coat over the varnish. There seems to be a temptation for many people to believe that Gibson and Loar made all the decisions on the F5 according to what would sound best, but many decisions were made for practical and production reasons, and the gloss coat over varnish was most like one of those, IMO. It didn't take them long to switch to nitro lacquer as soon as it was easily available. Finish time and cure time were reduced and a gloss could be had without additional steps. Coincidentally, lacquer showed up at Gibson about the same time LLoyd Loar left the building. What if the sequence of events had been reversed? What if lacquer had showed up at Gibson in 1921 or 1922 instead of late 1924? What if the F5 had come into production at the same time as the switch to lacquer? What if Bill Monroe's mandolin had been sprayed with nitrocellulose lacquer and signed by LLoyd Loar? Would as many mandolin players 'believe' varnish sounds better on a mandolin than lacquer, or would they, like many archtop guitar players, 'believe' lacquer sounds better? Well, we don't know, but I have my suspicions...

Nelson Peddycoart

Nov-17-2010, 1:22pm

Will Kimble does a French Polish over an oil varnish. If you take a look at the Mandolin Restoration thread, he has described and documented his process well. His mandolins are gorgeous.

I am ramping up for my first build and am doing a lot of research, particularly in this area. I am scouring builder sites, these threads and reading books on luthiery and finishing.

A few years ago, I read an article called the list of books that every wood worker should own. I think it came from Fine Woodworking. I owned some. Others I looked for on Ebay and Amazon. One of the best ones in the lot was by Tage Frid: "Tage Frid Teaches Woodworking - Book 2: Shaping, Veneering, and Finishing." It has a great section on French Polishing.

I have been told that Nitro Lacquer starts to break down after 50 or so years. If that is true, a non-lacquer finish would be a better choice for a future family heriloom.

Avi Ziv

Nov-17-2010, 1:45pm

John - thank you so much for the insight and detailed explanation!

One related question - what would be the approximate wait time from the varnish to FP steps? What would you look for to determine if it's "time" ?

And Nelson - thanks for the pointers. I'm in a similar stage as you - gearing up for my first from-scratch build.

Thanks

Ed Goist

Nov-17-2010, 2:16pm

FYI, I refined my Google search on this topic and found this informative site (http://www.lmii.com/carttwo/FinishOverview.htm). It's a basic overview of finish options for musical instruments.
Good, general background information here for the un-initiated like me.
Comments?

sunburst

Nov-17-2010, 4:12pm

Comments?

Good info for the most part, but I haven't been hearing the good reports on waterborne finishes that they mention. It's been said that the main ingredient in waterborne finishes is wishful thinking.
Rolfe has about the most experience with waterbornes of anyone I know. I know he is having some success with it, but I don't know where he is with it as of now. Perhaps he'll happen along here and maybe say a few words.

Lefty Luthier

Nov-17-2010, 5:47pm

I have been told that Nitro Lacquer starts to break down after 50 or so years. If that is true, a non-lacquer finish would be a better choice for a future family heriloom.

I don't agree with this statement. Recently I had the privilege of doing some fret maintenance on a mandolin that I built in 1962. The lacquer finish looked like new once I scrubbed off several layers of wax. I think that how an instrument is treated has far more to do with finish durability than time.

schloss

Nov-17-2010, 8:13pm

I would love to see some pictures of that '62 model ..Lefty. You should be getting credit for being one of the first, if not the first to build an F copy. Well done

Big Joe

Nov-17-2010, 8:44pm

Gibson began using nitro cellulose in 1925 and those instruments still do pretty well! Nitro is a good finish for musical instruments. Probably not the best for your kitchen table, but not too shabby for instruments. Any finish has issues, but with reasonable care and proper curing they can all be reasonably durable. Even the varnishes can be quite good and sturdy once fully cured.

Jim Hilburn

Nov-17-2010, 10:04pm

If you watch the Bennedetto archtop guitar video's when he describes the finish he uses he says "the traditional nitrocellulose lacquer". But during the golden age of the archtop, the 30's through the 50's it was traditional.

Rick Turner

Nov-18-2010, 1:41am

Wait a few years on that nitro. The span I've read is 75 years, and then it's really unstable. Of course a lot of nitro finishes go to Hades sooner, but the stuff will out-gas nitric acid and lose plasticizers (often castor oil) and will eventually check and start falling off the surface. Nitro lacquer is inherently unstable. Of course many vintage maniacs have made a high quality out of the checking of nitro. That doesn't mean it protects the wood well forever. To me, the finish on 1890s Martins, well kept, look a lot better than those from the 1930s. It's French polish vs. lacquer...

On the other hand, I shoot a lot of polyester and satin polyurethane, and I think they are terrific finishes if kept thin. Plus, I can, if pressed, do a complete finish in three days from bare wood to rubout, and that's without resorting to UV cure.

Lefty Luthier

Nov-18-2010, 10:33am

64918

Here is a photo of the mandolin that I built in 1962. This shot was taken in 2008 when the instrument was returned for a fret job and general update. It was built from dimensions that I took from a junked Gibson picked up from a pawn shop in Seattle for $8.00. I committed what in today's world would be heresy by dismantling that old Gibson to get all the dimensions and profiles correct. Wish I had kept that instrument, it would be worth lots of money today. One aside, that neck was reinforced with an Ebony spline, no truss rod, and is still straight after all these years under string tension. A good vote for walnut necks.

dunwell

Nov-18-2010, 11:09am

I've been pleased with nitro for everything except the back of the neck and the top. The neck back I seal with some sprayed shellac and top with TruOil FP leaving matte finish.

The tops with nitro have the problem of the final wet sanding. No matter how I seal the end grain in the F-Holes it seems to get in and swell the wood and crack the finish. What I'm considering is the following:
- spray seal with shellac
- spray or rub color coats
- top that and seal with 2 or three spray shellac coats
- FP with TruOil. Could do a shellac FP but it isn't as durable as TO.

I'd appreciate any comments on this as I have not yet done it. Of course I'd practice on scrap pieces but if anyone has experience I'd love to hear of it or alternatives of the same nature.

Alan D.

Jim Hilburn

Nov-18-2010, 12:57pm

Alan, never sand with water! Use mineral spirits. You'll never have that problem again.

dunwell

Nov-18-2010, 3:00pm

Alan, never sand with water! Use mineral spirits. You'll never have that problem again.

That would mean doing all the sanding in my spray booth because of the fumes. I could do that but it is a bit of a bother with my setup. Still, a good idea to avoid that problem, thanks.
Alan D.

Jim Hilburn

Nov-18-2010, 3:22pm

I'm sanding lacquer right now with Klean-Strip brand odorless MS from Home Depot. It really has nearly no smell. Trust me. My shop is right in the house and it doesn't smell the place up.
I bet you knew Denny Stevens. He told me to use DuPont Prep-Sol which is an automotive cleaner-solvent and it worked great but really stunk the place up. I still use PS to clean up the MS which is quite a bit more oily but you could use naphtha or (gasp!) kerosene as the final cleaner before spraying new coats.

sunburst

Nov-18-2010, 3:34pm

I've never had a problem sanding with water around the f-holes, didn't even know it could be a problem, but now that I know, it's sure to happen to me next time!
I've never applied Truoil right over shellac, but I have sealed with shellac, built the film with oil varnish, and then glossed with Truoil. I don't see any reason TO wouldn't work fine over shellac.

resophil

Nov-18-2010, 3:37pm

...- FP with TruOil. Could do a shellac FP but it isn't as durable as TO.

I'd appreciate any comments on this as I have not yet done it. .

I hate to point out what should be obvious...., but there is no such thing as French polishing with TruOil! The only technique called French polishing uses shellac!

If you are applying TruOil, you are not French polishing! I know that TruOil is the flavour-of-the-month with some finishers, but it's meant to soak INTO the wood (i.e. it's original purpose is as a gunstock finish, protection from the elements... It's more than 56% mineral spirits) It would seem that putting it over a couple of coats of shellac as a sealer would present a barrier to it being able to soak into the wood. And if you don't want it to soak in, what is it going to do on top of the shellac...?

Jim Hilburn

Nov-18-2010, 3:45pm

I always had water cause splits and cracks in the lacquer around the tuner holes.

Rolfe

Nov-18-2010, 3:58pm

Good info for the most part, but I haven't been hearing the good reports on waterborne finishes that they mention. It's been said that the main ingredient in waterborne finishes is wishful thinking.
Rolfe has about the most experience with waterbornes of anyone I know. I know he is having some success with it, but I don't know where he is with it as of now. Perhaps he'll happen along here and maybe say a few words.

Uh, how many is a few? For the past several years, I've had excellent results with KTM-SV. Looks great and wears well. Easy to apply, especially with the new Walcom EGO gun. No problems with body chemistry or other finish breakdown in normal use. And no complaints from the field. But it has to be done right, and I'll happily share that information with anyone.

dunwell

Nov-18-2010, 4:08pm

I hate to point out what should be obvious...., but there is no such thing as French polishing with TruOil! The only technique called French polishing uses shellac!

If you are applying TruOil, you are not French polishing! I know that TruOil is the flavour-of-the-month with some finishers, but it's meant to soak INTO the wood (i.e. it's original purpose is as a gunstock finish, protection from the elements... It's more than 56% mineral spirits) It would seem that putting it over a couple of coats of shellac as a sealer would present a barrier to it being able to soak into the wood. And if you don't want it to soak in, what is it going to do on top of the shellac...?

Interesting, resophil. Earlier in the thread we were admonished about FP being ONLY the process, not the material. ;) Be that as it may, I tend to agree with you that my brain thinks shellac when I hear French Polishing. Maybe it is a difference between "French Polishing" and 'french polishing".

In any case, TO is not my flavour of the week, I've been using it for a long time for various things, just not for the mando tops, thus my query. I do know it goes well over shellac. While it does soak into the wood on a first coat, not needing a primer coat, that is not really necessary for it to adhere well, and it acts as a harder, more water/arm-pit-goo resistant surface coat than regular shellac FP.

And thanks, Sunburst, for the thoughts with using oil varnish as the build coats, do you have a favorite brand/version? Do you spray or brush? I have zero experience with oil varnish in instruments, only table tops and rocking chairs ;)

Jim, for the tuner holes I reach in with a Q-tip loaded with something sealant-like, such as outdoor poly finish, keeping it away from the top surface, even before I shoot the lacquer. I then do the same thing with a tiny bit of johnson's past wax on top of that. That pretty much stopped the cracks at the tuner holes. The same thing did not work for the F-holes. Go figure! (missed you at the last get together)

Alan D.

resophil

Nov-18-2010, 4:40pm

...Maybe it is a difference between "French Polishing" and 'french polishing".

Actually, it's the difference between "French polishing" and "polishing." I learned to French polish in the classical way from an old vernisseur in the cabinet shop where I apprenticed. The closed-pore method of French polishing has been around for centuries, and is a time-honoured method of getting a truly high gloss finish on a piece of wood.

This method varies from what most instrument builders seem to do, in that succeedingly finer grades of abrasive are introduced into the slurry of the alcohol/ shellac mix at the beginning of the process. (These range from 4F pumice to rottenstone) The mixture of minute wood particles that are abraded from the surface, together with the pumice and shellac fill the pores and begin to provide a level surface, as the shellac mixture is fed from the "tampon." Gradually, the pumice is eliminated, as the micro-thin layers of shellac are built up over many days. The final polishing is with pure alcohol, in order to remove all vestiges of the lubricating oil.

With care and experience, this method (and it IS the method I am talking about...) will provide a surface of the highest measured gloss possible!

Open-pore French polishing omits the abrasive, and is generally more applicable to wood with tight grain and small pores. The pores will still be filled, but the process takes a bit longer.

Rubbing an oil finish is just that... All oil finishes generally need to be rubbed out.

sunburst

Nov-18-2010, 4:41pm

...do you have a favorite brand/version? Do you spray or brush?...

Favorite? As you know, finishes are all horrible, how can I have a favorite?;)
The lesser of the evils I've tried, though is Behlen's Rock Hard Table Top Varnish. I've also tried it mixed with Behlen's Water White Restoration Varnish. I've sprayed it, mostly, but I tried brushing it to try to simplify the process and confirmed what I already know; I'm pretty good with a spray gun and not so hot with a brush. I ended up brushing on coats until I had the film build I wanted, then level sanded and sprayed a coat or two to fix all the stuff I did with the brush.
I've thinned it with Behlen's Rock Hard Reducer, and with mineral spirits (pretty much the same stuff), and last time I tried it reduced with lacquer thinner(!) on the advice of John Monteleone who said it works fine and speeds up drying so dirt, runs and sags are less of a worry.

Resophil, the process you describe is the process used by many (if not most) classical guitar builders, though some are experimenting (with good results) with filling the wood with resin (epoxy or other) rather than pumice.

resophil

Nov-18-2010, 5:14pm

...Resophil, the process you describe is the process used by many (if not most) classical guitar builders, though some are experimenting (with good results) with filling the wood with resin (epoxy or other) rather than pumice.

This happens in the world of general woodworking too! If a job is just too big to be able to spend the time doing it in the traditional way, other fillers are used. I can see where epoxy resin might work really well on something small, like a mandolin. However, if I had to fill the pores on a large job, I would choose something with a longer open time... :)

sunburst

Nov-18-2010, 6:15pm

I've filled two guitars; backs, sides, and necks; mahogany and rosewood, with System Three 24 hour cure epoxy and it worked really well under lacquer. 24 hours is enough open time for me!:)
(To be fair about it, you don't really have 24 hours open time, but whatever it is, it's more than enough.)

Rick Turner

Nov-18-2010, 7:25pm

We use WEST Systems epoxy as a sealer/pore filler under anything else, and as long as you give it a light sanding and then wipe off the dust with a damp shop towel to get rid of any amines that may have formed on the surface, it's terrific. It wets the wood wonderfully to bring out figure, too, and I can use it over SolarLux or MEK stains. Great stuff, and yes, some classical builders are sealing with epoxy and then shellac French polishing over that. Tung oil (I use Waterlox) is great over epoxy, too, and I imagine TruOil would work well over it.

dwhite

Nov-19-2010, 8:40pm

I am surely no expert but I believe the only finishes that have really stood up to time are the spirit and oil violin varnishes. FP, I believe, has been around since the mid to late 19th century (I might be wrong about it, but the earliest stuff I've read is from the late 19th century).

Everything I've ever read about FP is about using shellac and olive oil.

I did not know an abrasive could be used for pore filling but that sounds like a great idea. I did find a site once that described finishing a commercial mahogany bar top using a rubber filled with pumice and wet with shellac. The author swore that it was bulletproof and had been on the bar top for decades. (By rubber, I mean the pad you use, actually, in this case, an old wool sock).

From what I read, FP was abandoned early in the 20th century on furniture as labor costs increased. I believe the very top of the line classical guitars are always finished with FP. I would think FP would be a very respectable finish, although you would have to take good care of the instrument. Just pretend you're a violinist; they take really good care of their instruments.

I'm also pretty sure that the finish should sit on top of the instrument, not in the wood itself.

resophil

Nov-20-2010, 1:39pm

When trade routes by sea opened to the Orient in the 1600s, things other than spices made their way to the western world. What we know as "shellac" has been in use as a wood finish in the Orient for a long time. Just because it doesn't show up in western literature doesn't mean that it wasn't in use. That's a pretty insular view of the world...

In Japan especially, another technique, the use of the sap of the "lac" tree ( rhus vernificera or 'Rhus Verniciflua) has been used as a wood finish for a thousand years or more. Search for the term "urushi" There are documented cases of wooden objects finished with this technique surviving 300 years of immersion in seawater in shipwrecks, and being unharmed upon salvage.

Wood finishing techniques were in use in the Orient that made western methods pale by comparison of effectiveness and beauty. This parallels equivalent advances in things like metallurgy. Laminated forged-steel plane blades were in use in the Orient while we in the west were still smoothing wood with an adze. Who do you think was able to produce smoother wood surfaces?

Yes, French polishing is a labour-intensive method of finishing but it hasn't been and wasn't totally abandoned. I have done big and small jobs. The largest was the panelling for the lobby of an upscale office suite for an IT company. French-polished rosewood! It gleamed in there when we were through!

I doubt the story about the French-polished bar top. Shellac's biggest drawback is that it is susceptible to damage from alcohol, which is it's solvent. Spill a drink on a French-polished surface and you immediately mar it. Why would you choose French-polished shellac as a finish for a bar top where alcohol would certainy be spilled? It certainly wouldn't be bulletproof!

What you call a rubber, I called a "tampon" above. It's the French word. I use pieces of well-washed linen in which I twist a saturated old wool sock, which releases the shellac/alcohol mix in just the right amount. The pumice is just dusted lightly on the surface while you are working. I add mineral oil as required to keep the pad from sticking. Just a drop or two from a fingertip...

On your last point, we agree! I'm going to try some experiments with epoxy sealers in my next projects.

dwhite

Nov-20-2010, 7:00pm

Here's an article that mentions FP as being the standard finish of the 18th and 19th century (in Europe). He says the first mention of shellac in Western literature was in 1590 by an English writer who discovered it in India. There are lots of ways to shellac as you know, FP being one of them so you can't be sure that just because there was shellac, there was FP.

http://www.helium.com/items/643879-what-is-french-polishing

Wikipedia says it came into peak use in the victorian era and was largely abandoned by 1930 (I know some people still did, certainly classical guitar makers have an unbroken history).

frets.com gives 1925 to 1930 as the period when FP was discontinued by manufacturers in the US. http://www.frets.com/fretspages/luthier/Technique/Finish/FrenchPolish/frenchpolish1.html

In case anyone is interested, here is a series of newsletters that describes how to french polish: http://www.refinishfurniture.com/french_polish.htm

The one I got my best info from is: http://www.milburnguitars.com/fpbannerframes.html

As for the pad, I ran across the term muneca many times in many articles.

I know what you mean about the bar top. I hope to find the article and post it. The person filled the tip of the sock with, I think, pumice so I imagine a lot got deployed into the finish (and perhaps into the wood?).

resophil

Nov-23-2010, 11:57am

...The person filled the tip of the sock with, I think, pumice so I imagine a lot got deployed into the finish (and perhaps into the wood?).

I think you may be a bit confused about methodology of actually applying pumice to the working surface while French polishing...

In the days of the use of quill pens and rag type paper, a newly written passage in ink on a piece of paper was often dusted with a substance of some kind to absorb some of the ink, coagulate it, and stop big blots from happening when the paper was folded. Pumice was used for this, as was ground bone or chalk. This was dispensed from a "pounce" (or "ponce") bag by lightly shaking it over the paper. Some of the powder would dust out of the fabric sack and do it's work on the paper.

The vernisseur used the same technique to get a very light dusting of pumice on his wet finishing surface, but the bag with the pumice in it NEVER touched the wet surface. If it got wet, it wouldn't dispense anything! And wool would be much too coarse a fabric to polish with. It's used because it will absorb the alcohol/shellac mixture and ooze it out slowly as it is twisted inside the linen tampon.

Getting all your information from the internet is fraught with danger and assumptions...

dwhite

Nov-24-2010, 8:21am

I think you may be a bit confused about methodology of actually applying pumice to the working surface while French polishing...

In the days of the use of quill pens and rag type paper, a newly written passage in ink on a piece of paper was often dusted with a substance of some kind to absorb some of the ink, coagulate it, and stop big blots from happening when the paper was folded. Pumice was used for this, as was ground bone or chalk. This was dispensed from a "pounce" (or "ponce") bag by lightly shaking it over the paper. Some of the powder would dust out of the fabric sack and do it's work on the paper.

The vernisseur used the same technique to get a very light dusting of pumice on his wet finishing surface, but the bag with the pumice in it NEVER touched the wet surface. If it got wet, it wouldn't dispense anything! And wool would be much too coarse a fabric to polish with. It's used because it will absorb the alcohol/shellac mixture and ooze it out slowly as it is twisted inside the linen tampon.

Getting all your information from the internet is fraught with danger and assumptions...

No, I understand now how to use pumice, I was just relaying what I read. And I know what you mean about bad information on the internet. I'm completely self taught and my only source of information is on the internet. That's where I got the recommendation to mix hide glue 50/50 and to use the strongest you could find, at least 315. That's fine if you are the flash and can work withing a 15 second working time but for the rest of us subsonic people, it just won't work. I thank the fine folks here for straightening me out about this.