FastForward - 8-19-2010 at 03:05 PM
I wonder whether it is good/recommended/bad to seal the inside of the oud using Shellac, Tung Oil, Tru-Oil?
The purpose is moisture resistance.
Which one of these would be most recommended?
SamirCanada - 8-19-2010 at 03:34 PM
In my humble opinion it is not a good idea.
I would imagine that in that situation the face of the oud would move quite a bit more then the back with changes in humidity. I have a feeling it is
probably better to allow for the movement to occur at the same rate for every part of the instrument.
Also, the master's instrument that remain with us didn't have finish on the inside I don't believe.
fernandraynaud - 8-19-2010 at 03:42 PM
From what I've seen, the traditional approach is always raw wood and paper strips. I don't know if anyone has done it otherwise, though I have one oud
whose maker slathered glue for reasons that only his doctor can explain. I would be worried departing from tradition for the following reason. The
sound of an Arabic oud of the Egyptian variety, what we have started to call the "longing homesick" type, relies in a very complex cancellation of
some partials and a bounce of others. The short sustain is not due to lack of resonance but to a very selective handling of the sound wave, resulting
in something like a slap echo and a phase canceling of the fundamental. If your oud is a Turkish or a very resonant say Iraqi, the concept of coating
the inside isn't as scary, but if you have a good Egyptian type sound, or any subtle timbre you love, for that matter, I wouldn't dream of altering
the inner surfaces, as we don't have a full grasp of what does what. You could find your oud completely altered, for the better, or the worse. How
brave are you? 
Structurally Samir makes a very good point too.
Why are you so concerned about moisture? If you paint the wood, it won't prevent humidity from penetrating anyway. Is the concern growth of fungus or
weakening of the glue? Most ouds bowls hold together by geometry even if the glue is gone. You could delicately treat the inside with an
antibacterial solution, there's that stuff Aymara swears by.
Sazi - 8-19-2010 at 04:40 PM
I read a post from Oudmaker Thabet Al Basry on his own forum where he say's he seals the inside of every oud, including the face, for moisture
protection. His ouds have a fairly good traditional sound regardless. I don't know about the "tradition" part anyway, it is a living tradition and
there are almost as many variations as there are luthiers. Some Greek luthiers even line their bouzouki's with copper foil, I don't know that it makes
too much difference to the sound or structural integrity. As far as moisture getting in anyway, sealant or not, at least sealed the change in moisture
content would be more gradual, and therefore less stressful (for you and the oud!)
fernandraynaud - 8-19-2010 at 07:23 PM
Interesting. But of course it would have some effect on the sound, to the extent it makes the bowl surface more reflective, it would change
something. The ouds you mention sound the way they do after the fact, it's one element in their acoustics, and my point is that since we don't know
what contributes what, it's a change I would be nervous about making, though I'm not generally reluctant to modify an instrument, nor am I tied to the
"traditional". The bowl is not just an inert reflector. If someone had told me a few months ago that the species of walnut used for the bowl makes a
big difference in the timbre, I would have been rather skeptical. But I have been playing 3 different Sukars that seem to differ only in this respect,
two of them anyway seem structurally identical, yet they have different timbres, and they vibrate differently. No way to predict how coating the bowl
will affect FastForward's oud. It could make it better, louder, it could ruin it, or it could make very little difference. Maybe it's worth a try. But
is there a reason?
As to the whole notion of sealing the wood to reduce the effects of humidity, i'm with Samir. We also have several centuries of relatively documented
experimentation with respect to harpsichords. In four centuries here has been only one successful construction that reduces cracking and tuning drift,
and that's John Challis' design, which makes the entire string-bearing assembly, including the soundboard, out of aluminum. All other tricks have been
counter-productive. The massive steel and lacquered wood harpsichords of the early 20th century stretch and crack and warp worse than the traditional
light wood instruments of the 18th century, they produce a fraction of the volume, sound tinny, and are now considered good only for e-bay. Except for
a few metal parts that can be much better made nowadays, and allow for adjustment convenience, good harpsichords are now made the "traditional" way,
even using 18th century plans, not out of slavish obedience to the past, but because it turns out it's what works.
FastForward - 8-19-2010 at 08:58 PM
Samir: I see your point of view though I am not sure how different parts will move at the same rate. The face is already a different kind of wood and
its reaction to humidity is different from the back. I know traditionally this hasn't been a common practice that is why I am asking.
Fernandraynaud: I am not sure how the oud will sound yet and as you suggested sealing the inside can cause some tonal changes (favorable or
unfavorable). I am aiming for moderate sustain because too much sustain doesn't sound well and too little makes the oud very dry.
I am definitely not worried about fungus or the like. I am just worried about the structural integrity of the instrument in humid conditions cause
hide glue was used to join the parts. I realize that hide glue has been used for ages successfully so may be I am just too worried.
Sazi: I think I have read the same post you mentioned, I think there are a couple more Iraqi or Kuwaiti makers who seal the inside as well. I also
think that Ali Hassan has done it but not 100% sure.
Here in SoCal the humidity is not a big issue so I guess for now I will keep the inside bare and applying shellac in the future won't be hard.
FastForward - 8-19-2010 at 09:00 PM
Also, I noticed some makers apply a strip of paper on the inside of the face where the two pieces are joined. I am not pro this but wondering if this
does reinforce that joint and makes it stronger or protects it?
fernandraynaud - 8-20-2010 at 06:31 AM
Most ouds survive a long time in widely different climates. Considering they are utility items that get beat up and sat on, it's not surprising there
are no 16th century ouds around, same with lutes. But there are a number of 100 year old ouds that are playable. I wouldn't worry about it falling
apart, and if a joint lets go, with hide glue it's easy to fix. So I would just enjoy it the way it is.
Abo Zaina - 8-21-2010 at 11:34 AM
for applying shellac it is meant to work as a sealer that enhance the bowel's ability to reflect the sound and to protect against humidity so it is
one single coat with little fine sanding.
When I moved from Jordan to UAE the high humidity in UAE ruined both my ouds withen 2 years although one of them I didn't take outdoors. Now I have
one that has a single finly sanded coat of sealer then another thin coat of shellac, it has been 6 years and so far so good, I even take it in fishing
trips.
what I don't know is in what order do they do it (gluing paper strips then sealer and shellac or what?)
hope someone got an idea about it
FastForward - 8-22-2010 at 03:54 AM
Abo Zaina: Thanks and your point stands and that is the main reason I am thinking of sealing the inside. The whether here in LA is similar to Jordan
and is not too humid. But in other places in the US or Gulf it is very humid and I can see that the humidity can damage the oud.
I think the order would be paper strips then shellac.
fernandraynaud - 8-22-2010 at 06:10 AM
I don't understand. You said you live in LA. Are you planning to move to the Gulf Region soon? If you put it in high humidity, or out in the desert,
do you really think that a little shellac and some paper is going to prevent it from equilibrating to that air? I don't see it.
FastForward - 8-22-2010 at 06:35 PM
Yes, I live in LA down south from where you are. No, I am not planning to move to the Gulf region, but I may be moving to the midwest/east cost where
it is way more humid than even the gulf.
Yes, some shellac or an oil sealer will prevent the humidity from weakening the glue joint. It acts as a barrier unless of course the sealing material
is water permeable.
In any case, I don't what I was thinking today but I applied a coat of tru-oil to the inside, I was thinking I can alway sand it.
My observation was that the resonance inside the bowl was much higher than before. I am guessing this is due to the reflectiveness of the surface.
Also the smooth finished inside looks neat.
fernandraynaud - 8-22-2010 at 11:38 PM
Well, so at least you've confirmed you can impact the acoustics.
If it makes you happy ...
Sazi - 8-23-2010 at 04:50 AM
Sounds good to me, I love really resonant ouds.
We don't have tru-oil here, and no-one I've asked seems to know of it or if we have an equivalent.
FastForward - 8-23-2010 at 11:39 AM
fernandraynaud, its not about making me happy. I don't know how it happened, I was on/off for the idea and all of sudden I realized that I am spending
to much time thinking about it than executing either way.
Sazi, I do not know where you are located but you can probably find things that are similar. Tru-Oil is a mix of Linseed oil (زيت
حار
and Tung oil and some other stuff to make it polymerize and
dry faster. I know Linseed oil is available in the middle east, but as is takes for ever to dry.
sabbassi - 8-23-2010 at 11:08 PM
Never use shellac or seal the wood inside the bowl. it need to be as natural as possible. No violin or guitar maker have done this as far as I know
This is where the wood quality is a major rol player. Some wood are more resistance to humidity and life than others. cheap wood will crack or bend
sooner thand hardwood like rosewood or Maple
the paper strips are glued with hide glue to the back and offcourse when you apply hideglue it kind of seals the joints and big part of the ribs. Hide
glue will not effect the sound as much as other sealers do.
after all this is my oppinion 
Jonathan - 8-24-2010 at 10:53 AM
For what it's worth, Peter Kyvelos does coat the inside of the bowl of his ouds.
The Guild of American Luthiers had a great two-part article on Kyvelos a couple of years ago--"constructing the middle eastern oud with Peter
Kyvelos".
It's really a very very good article--spread out over two issues of the magazine, though, so make sure you get both. It is extremely helpful to
anybody interested in the process of oud making (most of us, I guess).
There, it says that "the entire inside surface of the bowl will get a few coats of shellac or varnish to seal it and help reduce dimensional changes
with changes in humidity."
There really is no definitive way to make ouds, but I really respect Kyvelos and his instruments.
I'm finishing up my fifth oud right now, and, for the first time I did put on a coat of shellac.
FastForward - 8-24-2010 at 11:16 AM
Samir, thanks.
At this point I have already sealed the inside. I am sure it will affect the tone somehow, my initial assessment was that the inside was more
resonant, or reflective. Anyway, if I see that it is cause problems then I can always remove it. I have already assembled the face and things can be
done through the rosette holes.
I have seen Guitars sealed on the inside. I think there is a significant difference between the oud and the guitar in the sense that the oud has many
more glue joints than a guitar. Hence, its more susceptible. The paper strips do reinforce these joints but humidity seeps through the paper.