Replies

1. 
   brnaclbil | Feb 18, 2004 07:26am | #1

   Jazzdog,

   That sounds interesting. Do you have before and after photos?

   Thanks,

   Bill

1. 
   jazzdogg | Feb 18, 2004 07:57am | #3

   BB,

   All I have so far is "before" and "during" photos; the "after" photos will be taken after I'm done finishing.

   BEADG,-Jazzdogg-

   Whether you think you can, or you think you can't, you're right.

2. 
   Agee | Feb 18, 2004 07:41am | #2

   Jazz,

       I assembled a Wharmoth PRS copy a few years back.I used a water based dye from Stewart McDonald (stewmac.com great guitar builder supply company) then sanded it lightly to take the dye off the high spots to make the curly figure really pop.I didn't have a spray gun,so used their nitrocullulose lacquer in a can.It turned out GREAT!!! Just don't spray the lacquer in high humidity or it will blush.

   Mike Agee

1. 
   jazzdogg | Feb 18, 2004 08:00am | #4

   Mike,

   Thanks for your reply. This is a fun way to change the daily pace of furniture & cabinet making, isn't it!

   Here's to intonation,-Jazzdogg-Whether you think you can, or you think you can't, you're right.

3. 
   JBD | Feb 18, 2004 08:09am | #5

   The oil will give you deep color, but I would finish it in a faster way, almost or possibly equal in deep rich color.  The multicoats of lacquer will be soft, not durable, and will give you the "dipped in plastic" look if too many coats are applied. 

   Consider sealing and filling the raw wood with boat epoxy, like West System (use the no-blush hardener # 207).  Then sand and coat with lacquer (if you wish), or I would spray automotive urethane.  This is faster, will still telegraph wood grain a little (to avoid the plastic look), and the epoxy will darken and enrich the color quite well. 

   You run the high risk of the lacquer and shellac peeling off if the oil is not completely evaporated/cured.  FWIW.

    

   "The furniture designer is an architect." - Maurice DuFrenes (French Art Deco furniture designer, contemporary of Ruhlmann)

   http://www.pbase.com/dr_dichro   http://www.johnblazydesigns.com

1. 
   jazzdogg | Feb 18, 2004 08:13am | #6

   Thanks, John.

   It's always nice to receive a response from a gentleman as qualified as you are!

   Low notes,-Jazzdogg-Whether you think you can, or you think you can't, you're right.

1. 
   Fingrs | Feb 18, 2004 08:46am | #7

   Hello, all.  Last week I took a tour of the Martin Guitar factory in Nazareth, PA, and was so inspired by the woodworking I saw there that I bought one of their kits.  The sides and back are rosewood, which I've never worked with before.  (I do all my furniture work in cherry). 

   By the way, the Martin factory tour is a "must see" for woodworkers...they do most of the work by hand using simple tools many of us have in our shops. 

   I want to make sure the sides and back are filled and finished properly to give good protection to the instrument as well as great sound, but do not know how the finish will affect sound.  I don't want the "wet" look so many people seem to prefer, but acknowledge that such a finish (by virtue of its thickness) probably adds rigidiy to the instrument's body.  So, after all this rambling on, just what is the role of the finish in determining the sound of the instrument?  Should the back and sides be "rigid", and the front "flexible"?   

   What is a good approach to this task?  I do not have spray equipment. 

   If the answer is too lengthy, I would appreciate a reference to a reputable book or other source.  I paid close to $500 for the kit and don't want it to sound like the $20 guitar I had when I was 12 and dreaming of becoming the next Beatle...

1. 
   OneofmanyBobs | Feb 18, 2004 03:38pm | #9

   For an acoustic guitar, thin and hard.  Thin is the key word.  Thickness adds mass and that kills sound.  You'll get a lot of debate here, but shellac gives a great sound.  Its not as durable as nitro.  Any thick finish will mute the sound, as will a softer finish.  So, options are 1) nitro (spray it only), 2) nitro on the back/sides and shellac on the top, 3) all shellac.  All can look beautiful.  All take practice.  All have their own issues.  Shellac should be French polished.  It is not easy to do.  Nitro must be sprayed.  You can get it in spray cans.  Not acrylic or automotive or other home-center type lacquers.  Actual nitrocellulose instrument lacquer.  Surface preparation is not just important.  Surface prep is 99.7% of a good job.  Pore filling is the hardest part of French polish.  Some very reputable folks use epoxy or cyanoacrylates.  Its faster and reliable.  Will it last 100 years?  Nobody knows.

   Read several books first.  Check LMI and Stewmac.  Practice on many pieces of scrap and on furniture.  Have patience.  In my opinion, finishing is harder than then the woodworking part of instrument building.  You can hide a lot of little things inside the box.  Unless you play the instrument in the dark, the finish is what people see and judge.  There's no quick answer.  People spend their entire lives on the subject.  If you read a lot and practice a lot, and are exceptionally attentive to details, you can do a good job on your first instrument.

   Go to mimf.com, the musical instrument makers forum.  Read everything they have to say before picking up your belt sander.

1. 
   Fingrs | Feb 18, 2004 04:11pm | #10

   Thank you for the very robust response, Bob.  I agree that surface preparation is 99+%...and I will practice, practice, practice before applying finish to the instrument.  And I'll check all ther references as well.  This is exactly what I was hoping for in my post.

   For the front of the guitar, do you think I could use a satin gel varnish, such as that from Bartley?  I use this on all my cabinets and furniture and find it to be very durable, as well a providing a delightfully soft finish.  For cherry, I typically sand using a random orbit sander through 220 grit then hand sand to 320.  This is followed by a mininum of three coats of varnish.  It seems "hard" to me, and is definitely thin.

   I'll assume you were kidding about the belt sander...I use that only on oak floors at this point! 

2. 
   OneofmanyBobs | Feb 18, 2004 09:11pm | #13

   There are a hundred books on the subject, a dozen or more good ones still in print.  Lots of good information and lots of bad.  Furniture and instruments are two different worlds.  I would not use the gel varnish.  It might work, but...  when I have 80 or 200 hours into something, I'm not too interested in experiments.  There is silica in that stuff to make it satin, plus additives to make it jello.  I want to make it flawless.  I invest a huge lot of time in the wood to do that.  I don't want it slightly hidden with satin varnish.  I do French Polish mostly.  Takes much practice and not an industrial-strength finish.  I like the look and like the sound.  You don't leave the instrument in a hot car over the weekend.  Nitro is also fine.  Tried and tested.  Appropriate and expected for a good steel-string.   Other stuff is in the "kids, don't try this at home" category. 

   Like it or not, conformity is the watchword of the profession.  It is expected that certain things look a certain way.  "Gee, this sounds great.  interesting finish you have there.  Let me see that other one."

   There are three functions of a finish:  Don't foul up the sound - Beautify - Protect.  Put them in your desired order of priority.  If you're commercial, add cost into the equation.  How much the finish, equipment and labor cost.    I put them in my desired order.  No point in building it if it won't sound good.  I can buy something that looks pretty much like a guitar from k-mart for $49.  Make it look nice is second.  Protection is last because you can work around that with care, and with the right finish it is repairable.  Cheap commercial stuff is the reverse.  Cost first.  Roll on a coat and you're done.  Durability next.  No callbacks.  Beauty next.  Almost looks like it might be wood under there?  Done.  Sound?  "Thump".  Yep, it makes a sound, ship it right out. 

   Now, to balance sound and playability and looks and durability; that's the art and difference between a $50 and a $500 and a $5,000 instrument.  You have $500 invested in the wood.  Way easy to make that worth $50.  Way hard to make it worth $5K.  Some of this stuff has been done the same way for 500 years.  There are reasons.

3. 
   Kell | Feb 18, 2004 09:47pm | #15

   FWIW I made an acoustic dreadnought based on a Martin D-18 about 6 years ago.  The finishing process I went through is as follows:

   Grain filling with Pore-o-pac filler on the back and sides (Rosewood) and tinted with black dye.  Rubbed off with burlap after it hazed over and allowed to dry for several days.

   Sprayed sanding sealer over entire guitar surfaces and allowed to dry for a day.  Sanded with 320 grit all over.

   Sprayed nitro lacquer, from a can as I didn't have spray equipment at the time.  Shot 5 coats on the sound board and 9 on the back and sides.  I did this in one day as the weather and humidity were perfect for spraying.  (Old shop was unheated.)

   Allowed top coats to rest and shrink back for two weeks.  (The wait was horrible but worth it.)  After two weeks sanded with 600 and then 800 grit wet papers with water with a drop of soap for lubricant.  After getting a soft satin look all over, I wiped it down and waited 3 days.  Then rubbed out with pumice and finally rottenstone.  (This is the same technique I used on a queen anne desk that I'd made some years before and the finish turned out beautifully.)

   The finish on the rosewood really popped the grain and had a wonderful look on the spruce sound board as well.  The guitar had a terrific voice when I first strung it up and it has gotten richer over the years.  The owner, who writes music on a semi-professional basis, asked his session player to use it on a couple of demos that he recorded in Nashville last year.  That player, who owns many guitars and has played hundreds, told him it was one of the best sounding he'd ever heard and wanted to know where he'd gotten it.  I'm not saying it was all the finish but it has to have some impact particularly when it continues to change voice, subtly, over time.

   I picked up this method from something I read in Stew Mac, I think.  Good luck.  I found it one of the most rewarding WW experiences ever.  This year, I plan to build one for me.

   Kell

4. 
   Fingrs | Feb 18, 2004 09:53pm | #16

   Thanks to all for the information and suggestions.  I'll take a look at French polish as well as nitro.  Kell, I'm glad to hear you were able to make a superior instrument from the kit.  One thing I can tell you is I don't want to turn my $500 investment (not counting my time) into a $50 piece of junk! 

5. 
   RoyinMD | Feb 20, 2004 01:43am | #19

   Frank Ford's webpage has a wealth of information.

   http://www.frets.com/FRETSPages/pagelist.html

   Enjoy, Roy

2. 
   VeniciaL | Feb 18, 2004 08:52pm | #11

   Lofton,

   It's been a long time since I've been to the Martin factory. I grew up in Philadelphia and bought my first guitar in 1958. I took it to the factory to be "set up" and they let me stay and watch while several technicians did the work, then gave me a tour. What a thrill! I imagine it's a lot bigger now.

   I have yet to build my own guitar, but that's a project I have set for this summer.

   French polish is the proper finish for your instrument.

   I'm always amazed at the fear that the technique strikes in the minds of finishers. I believe that masters of the technique want to perpetuate the myth that it's hard to do. I'd be glad to describe my technique. I assure you, it is no harder to apply than an oil/varnish finish (and oil/varnish techniques are almost universally described as "easy" and "foolproof").

   Contrary to most of the myths about it, it is a VERY forgiving method and the method is FAST! Days from start to final results, not weeks.

   French polish results in the most beautiful surface it is possible to impart to a piece of wood. Nothing else brings out the color, clarity and "fire" of the wood's character. It is both achingly beautiful and durable. It never looks plastic, but rivals glass in its gloss and clarity. It can be tough, hard and elastic (very important for a musical instrument to deal with cold checking and other wood movement). Best of all, you can easily and very quickly repair any damage (inevitable over the years as the instrument is handled, shipped, etc) or restore the entire finish to new whenever you wish. Repairs are absolutely invisible. AND, you can brag that your guitar is french polished, a rarity in today's mass-produced world.

   I don't want to hijack this thread. Let me know if you want a description of the technique.

   VL

1. 
   OneofmanyBobs | Feb 18, 2004 09:28pm | #14

   Yes, but .....

   Not as hard as some say, not as easy as others say.  Much harder to do on a guitar than on a tabletop.  A higher standard of excellence is expected.  lots of curves and detail make it harder.  No reason to be afraid of it, just way harder than spraying on a coat of Rustoleum.  The right finish for a Spanish, but not really expected for steel-string.  On the top, where it counts most, OK.  A lot of people do that and I like it.

3. 
   CharlieD | Feb 19, 2004 11:26pm | #17

   Lofton,

   You and jazzdog might enjoy the MIMF, Musical Instrument Maker's Forum, http://www.mimf.com. Lots of stuff like that there, and woodworking to a specific goal. Very intense site, pro lutiers all around. I lurk there a lot.

   Charlie

   I tell you, we are here to fart around, and don't let anybody tell you different. --K Vonnegut

1. 
   Fingrs | Feb 19, 2004 11:43pm | #18

   Thank you, CD.  I'll check it out.  Lofton

4. 
   OneofmanyBobs | Feb 18, 2004 03:09pm | #8

   I wouldn't do it that way.  You're putting a harder finish on top of a softer one and that's asking for trouble.  You also risk cutting through when rubbing out.  There are a couple tried-and-true schedules and I'd stay with one of them.  All oil - use Tru-Oil finish.  Harder and higher build than danish or tung.  Semi-gloss, easily fixed, but not wet-look.  Or, traditional nitrocelulose lacquer.  Gloss.  There are semi-gloss that look like plastic and you could steel wool the gloss, but it will gloss back up on the wear areas. 

   Lacquer sanding sealer - as many coats as needed to fill the grain, but sand back to leave none on the surface.  The final job will be only as good as the quality of the surface at this point.  Make it perfect.  Wait.  Wait long enough for it to fully sink in the grain.  A week.  Three if you're patient.  Sand it back after a day and it will shrink and show grain.  Dye first if necessary, and stain again after sealer if necessary.  Or, tone the first coat or two of lacquer.  Vinyl sealer - spray one coat and do NOT sand.  6 or 8 coats of lacquer.  Wet sand any real bad spots between coats, but only when and where necessary.  Rub out.  I don't care for the waterbase products.  Still not as good and can be VERY hard to use.  Tight schedule, have to recoat within the time window or get bonding problems and witness lines.  The only way to do this is spray.  You can do it over 5 times with a brush or do it once by spraying.  You can buy the lacquer in spray cans from StewMac if you don't have a rig.  Still better than brushing.

   There's a reason why luthiers are so picky about finishing.  Its hard.  Many many ways to mess up and only a few that actually work.  Get the Erlewine book on finishing from StewMac.  Buy all the finishing products as a compatible set - all the same brand.  Follow the instructions exactly.  If you mix and match, you're asking for trouble.  If you want to lacquer over an oil finish, wait a year.  I would maybe think about it in 6 months.  It does not fully cure in a week or even a month.  Sandwich shellac between lacquer and oil, there's no place for the alcohol to go.  99% evaporates fast.  That last 1% takes ages.  As a sealer, fine.  The alcohol will migrate through the wood.  Sandwich it so it has no place to go and you will have a problem.  Not today or tomorrow, but soon enough.

   A nice nitro job does not look plastic.  It looks like a nice nitro finish and it is repairable.  The factory super-thick catalyzed finishes can look plastic.  They use it because it cures in a day, not because its good.

1. 
   jazzdogg | Feb 18, 2004 09:06pm | #12

   Bob,

   Thanks for your thoughtful reply. You've provided a lot of valuable information to consider.

   GBDFA,-Jazzdogg-

   Whether you think you can, or you think you can't, you're right.