Zulu - 10-5-2010 at 02:12 PM
The web site Monica's Guitars was suggested concerning finishing a soundboard; click on her Articles link and select Egg
Wash.
http://www.monicasguitars.com/
In her process she mentions using a nitrocellulose spray lacquer after the egg wash.
Does anyone have any experience with this method?
Below is the entire article...
When you have completely sanded your guitar and are getting it ready to apply a finish, you can first give it an egg wash. It is used to raise the
grain and leave behind a very fine seal.
Earlier this year, when the NAMM Show 2005 was held at the Anaheim Convention Center, a friend of mine, Josep Melo (http://www.meloguitars.com) from Barcelona, came out to display his guitars at the show. I met Josep at the Jose Romanillos workshop. He is a very
close friend of Jose Romanillos and a fine guitar builder.
During his week stay in Southern CA he was kind enough to share many of his trade secrets. Most of the questions I had were related to finishes. I was
ready to put a finish on the guitar that I had built in Spain with Jose Romanillos. My plan was to apply a French polish to that guitar and
nitrocellulose spray lacquer finish on another. He told me to first apply an egg wash regardless of what finish I was going to use.
The purpose of the egg wash is to raise the grain after sanding and just before sealing the wood before the finish. Normally you can just dampen the
wood with water after sanding to raise the grain. It also leaves behind a very fine layer which helps coat and seal the wood before the sealing
process. You really cannot see what is left behind after the egg wash.
The process consists of cracking an egg and separating it into a small cup or bowl, leaving only the egg white. Making sure that there is no trace of
egg yolk in the bowl because once you introduce the yolk into the mixture, it can spoil the egg. It is not necessary to mix the egg white prior to
application. Use a small paint brush to first apply the egg on all areas of the guitar that have colors that can bleed. Use the same process as if you
are starting to seal the instrument right before applying your finish. Apply the wash on the soundboard first. Continue to brush on to the back and
sides. Brush it on all parts of the guitar. Brush throughout until you finish the egg. Let it dry completely before fine sanding the raised grain, he
recommended to dry overnight. You are now ready to apply your finish.
I asked Josep how many eggs are necessary for the process, and he replied that only one egg is necessary for the process to coat a full size guitar
once or twice. I told him that it was a waste of a perfectly good yolk. He told me that if I save the yolk and add a few more eggs, mix in some onion,
potatoes and olive oil, I can make myself a great Spanish tortilla.
Brian Prunka - 10-5-2010 at 03:54 PM
Not with ouds, but I have some experience with spraying nitro lacquer, and I will tell you it's very toxic stuff. You have to be very careful, have
proper ventilation and wear a respirator. It is also extremely sensitive to dust, and can take a month or more to fully cure. Proper ventilation is
needed during the curing process (at least the first day or two after spraying), as the finish continues to release toxic compounds while curing.
It is a good instrument finish, though, with minimal acoustic impact, good protection from liquids and accidental bumps and scratches, and a nice
shine, too. I would think it would make an excellent finish for the oud's bowl, though I would still hesitate to use it on the face. If one was bent
on finishing the face, it wouldn't be the worst choice, though french polishing shellac would probably be a better option.
Zulu - 10-5-2010 at 09:22 PM
I'll look for posts on how to french polish shellac.
Thanks!
FastForward - 10-5-2010 at 09:30 PM
Zulu,
Check these links for more info on french polish
http://www.ehow.com/how_2084130_perfect-shellac-finish.html
http://www.shellac.net/Shellac-FrenchPolish.html
http://www.milburnguitars.com/fpbannerframes.html
http://www.guitarsint.com/article.cfm/ArticleContentId/1
http://www.finewoodworking.com/Materials/MaterialsArticle.aspx?id=2...
Some people would also recommend using Tru-Oil, here are links on how to use it
http://educ.jmu.edu//~dehartcg/finish.htm
http://www.lmii.com/carttwo/truoil.htm
There are also a few videos on yourtube that can be a little bit helpful. The worst part about french polish is grain filling with pumice, if you
decide to do it differently it might save you some effort. Good luck.
fernandraynaud - 10-5-2010 at 09:41 PM
The more you play the oud the more you appreciate that it's very different from a guitar. It's a much lighter instrument, more resonant, though the
tensions are much lower. Yet a good oud is quite loud. The interplay of the bowl and the soundboard is very different too. The whole oud vibrates much
more than the typical guitar. It's what makes the use of piezo pickups so difficult at high volume, as feedback is very pronounced.
All this to say that a guitar is to an oud as a rowboat is to a kayak. It's also a bit like a piano vs. a harpsichord. The state of the soundboard is
especially liable to impact the sound, and any finish must be very light, and brittle. By brittle I mean crunchy. The more you think about this, while
playing the oud, the more it will make sense. And try to play with your little finger pressing on the bridge! Half the volume disappears! The
time-tested finish on the oud's soundboard is the traditional: nothing.
Those of us who like to keep the face "pristine" with a barrier to dirt, are limited in choices. If you finish the soundboard the way a guitar
soundboard is finished, you can easily eat half the sound. If you goop the soundboard down with flexible stuff, like oil-finish, it will become quite
elastic and quite damped. On harpsichords it's the same. A well-intentioned varnishing can mute the sound of a harpsichord so badly it can take years
of sanding and working with solvents to recover the timbre. Only a light shellac and egg tempera decorative paintings are safe.
Nitro is OK on guitar bodies, but I doubt it will work well on an oud soundboard. Sprayed Nitro tends to go on way too thick anyway. The only finish
that is recognized as reasonably safe is a very thin (applied using French Polish technique or brushed on and sanded/steel-wooled down to a very thin
layer) shellac. It has worked well for me, and it's a good barrier to stains. Simple unwhipped egg white alone seems to do no harm, and can be buffed
to a lovely satin, but it's not a very strong protector, except inasmuch as it can be periodically steel-wooled to remove its top layer along with
superficial dirt, and a fresh layer applied.
The varnished ouds of Mohamed Al Cheapo Street are designed to hang in living rooms and elicit conversation, on this and that. Only their maker knows
what they sounded like before. Though they probably looked even cruder before they met the varnish pot, they might well have sounded better and
louder. But as "conversation pieces", like children, they are meant to be be "seen and not heard". No wonder their soundboards are heavily varnished!
It's interesting how some passes on the soundboard with steel wool seem to enhance their sound, as well as their looks.
Please, don't spray down that soundboard! As to TruOil, I have a lot of experience with polymerizing oils and "wipe-on-varnishes" that are built
around them, and I can tell you they are great for fingerboards, but about as appropriate on a soundboard as peanut butter.
There's only one type of finish that is used on fingerboards and that (by its physical properties) seems like it might possibly be very interesting on
a soundboard, and that's cyanoacrylate. But I've never heard of it being done. Maybe it has been done, but with such horrible effects on the luthier's
entire household, begining with small pets and children, that it has never been reported beyond the annals of emergency room medicine.
Brian Prunka - 10-6-2010 at 10:23 AM
To add to Fernand's post:
Even classical guitar makers do not use lacquer on their guitar soundboards. They may use lacquer on the sides and back of the guitar, but on the
face they use shellac. Of course I am referring to luthiers, not factory-made "classical" guitars--who knows what they use. So if guitar makers have
reason to refrain from lacquer on the soundboard, then it should go double for oud.
Tru-oil is a fairly light finish and is good for the bowl of an oud, but I agree it probably is not a good idea on the face. As I understand it, it
is actually a kind of varnish, not an "oil" finish in the traditional sense.
I've wondered what a true violin-type varnish would do to an oud. Those varnishes are very stiff.
Zulu - 10-6-2010 at 12:19 PM
If you've read any of my other posts you know I have a cheap oud(that I will henceforth refer to as my "beater")that I did a fairly decent job of
upgrading. Part of which was to finish a very grungy soundboard.
The soundboard was so gross that even after some light sanding some stains had been there so long(6 years)that they were deep into the wood; therefore
I chose an amber colored shellac.
After taping off the neck and bowl I brushed on egg white and let it sit 24 hours.
Then lightly sanded and brushed on a light layer of shellac and let it dry 24 hours.
I then buffed down to a thin dull finish with 0000 steel wool.
The oud is still very loud when played and when you tap on the sound board it rings...no dull thump.
I have to admit, after seeing the real french polish technique, it's a bit much for me to commit to doing myself.
My new Sukar 212 will arrive in 2 weeks and I plan to finish the soundboard the way I did my beater but will use clear shellac.
Below is a pic of my beater, it's hard not to have brush marks with colored shellac; though I believe the application should appear a bit more
seamless with clear shellac.
off topic...can someone please message me how to put small thumbnail pics on a post that enlarge when clicked on; Thanks!
fernandraynaud - 10-6-2010 at 02:06 PM
Yo, Zulu, if you upload an image using the Attachment feature of "advanced" mode, it will automatically gen a thumbnail.
I think your beater looks great. The only caution for your sukar is that I've found canned shellac tends to dry gummier than traditional flake in
alcohol shellac, so it's worth ordering some flake.
Zulu - 10-6-2010 at 02:26 PM
The canned shellac did get gummy as I applied it; I'll search the web for some flake shellac.
Thanks for the upload tip!