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Estebanana _Stephen Faulk
Oud Addict
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Doh!
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jdowning
Oud Junkie
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Before moving on to summarise the properties of egg white foam distillate a short test was carried out on the sound board of my old Egyptian oud
(currently undergoing restoration) to try to establish if any sort of invisible finish was present. The sound board shows no signs of localised
staining but has a darkish uniform patina. Initial thoughts were that a thin wax finish had been applied (as it had been to the bowl) - but could it
have been egg white distillate - or just no finish at all?
The attached images show the difference between a water drop applied to untreated Sitka Spruce compared to one applied to a waxed sample of Sitka
Spruce (Minwax Paste Finishing Wax). As might be expected the water on the untreated sample remained on the surface for about 30 minutes being
immediately but slowly and completely absorbed into the wood whereas that on the waxed surface showed no sign of being absorbed even after an hour or
so.
In comparison, the water droplet on the old Egyptian oud sound board showed the same characteristics as the untreated Sitka Spruce sample.
Had the sound board been treated with egg white foam distillate then the water would have remained on the surface until fully evaporated as is evident
in the previously posted images of the test samples.
Wiping the sound board surface with a damp cloth removed some oxidation and surface grime.
It is, therefore, concluded that the sound board originally had no finish of any kind - which is consistent with traditional oud making practice.
Some lute makers (e.g. the late Robert Lundberg) apply a thin hard wax finish to their sound boards which would certainly seal the surface against
water absorption. There is no evidence that I am aware of, however, to confirm that the old lute sound boards, like those of the oud, were ever
finished or sealed in any way.
Apparently, the old oud makers (working in the Turkish tradition at least) were very fastidious in preventing anyone but themselves from touching
their soundboards during the final stages of assembly - for fear of accidental (or deliberate!) contamination of the wood with oils that they felt had
a deleterious effect on the sound board response.
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jdowning
Oud Junkie
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To tie up the loose ends of this thread in summary:
Egg white foam distillate is not the same stuff as raw egg white. Raw egg white is clear and gelatinous whereas the distillate is a uniform,
transparent pale yellow liquid of low viscosity (watery consistency). It is considerably more alkaline than raw egg white.
According to food industry researchers, albumen is made up of a complex mix of protein molecules some that are attracted to water and some that are
repelled by water. Mechanical agitation of the albumen causes the protein molecules to denature - to open out into long chains that link together to
form a membrane or 'skin' around included air bubbles to create the stable 'egg white foam' of commercial interest to the food industry. The
researchers also report that the denatured molecules in the foam have been irreversibly modified characterised by the presence of sulphur atoms
(sulfhydryl and disulphide).
The volume of foam generated is dependant upon the time it is beaten (trial indicate that about 7 minutes is optimum). Stability of the foam is
adversely affected by the presence of moisture or contamination by traces of oil or grease - so equipment must be clean and the egg white beaten when
humidity is low.
When the foam is left to stand, the foam begins to break down as the molecules gradually lose their adhesion to each other (presumably because of
moisture in the air). The resultant distillate that drains from the foam after 14 hours or so presumably is a mixture of denatured water attracting
and water repelling molecules in a solution of water (as agitating the liquid distillate results in the formation of bubbles that are stable - lasting
for days).
When the distillate is allowed to dry out, by evaporation of the water content, a clear, brittle, gum like residue remains. This residue is readily
'dissolved' in water.
When the distillate is brushed onto sound board material it is immediately absorbed into the wood causing (temporary) swelling of the wood cells. When
dry, the surface treated with distillate exhibits resistance to water absorption. It is thought that the reason for this is that the distillate
residue absorbed by the wood is partially reconstituted by moisture. The molecules then immediately link together around any air trapped in the cell
cavities to form a stable foam preventing further absorption of moisture.
The alkaline distillate also has a chemical reaction with the wood perhaps resulting in a close bonding with the cell structure?
So wood treated with distillate should be a good sealer against moisture ingress which is perhaps why some violin makers report improved acoustic
response when the interior (not exterior) surfaces of their instruments are coated with distillate (or its variants) - the coating sealing the wood
against atmospheric humidity changes that can temporarily affect acoustic performance? Some even claim that cheap Chinese violins show dramatic
improvement when treated this way.
It has been demonstrated by these tests that the distillate can also act as a sealer for varnishes although when using oil varnishes it is usual
practice to first 'prime' the wood with thin, diluted varnish (or shellack). In the case of shellack, it is generally well known that shellack used by
itself is a very effective sealer of wood grain.
So - there you have it - in a nutshell:
If the top surface of an oud sound board is to be left unvarnished and otherwise untreated in the traditional way then there would obviously be little
point in sealing only the underside with egg white foam distillate to prevent atmospheric moisture ingress in order to gain some - as yet unproven -
acoustical stability or other advantage. However, if the sound board top surface is to be non traditionally varnished or shellacked then a sealing
coat of distillate on the underside just might show some benefit.
For those willing to experiment - let us all know the results. Good luck!
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Greg
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Thank you John. This has been an extremely interesting series and I sincerely thank you for your diligence and for sharing the results of this
important research with us.
Warm regards,
Greg
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antekboodzik
Oud Junkie
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Dear Sir John,
Did your trials confirm if using egg white distillate makes wood surface stronger, as mentioned by Cennini?
I am asking, because I wonder, if this sealer would be good for lute neck and pegbox, making its surfaces more resistant to make dents on it whentying
frets, or sometimes scratches of nail of the left hand thumb...
Is it also safe to use it on quite delicate, renaissance lute bowl? Wouldn't it distort the bowl?
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jdowning
Oud Junkie
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I doubt if application of the distillate would significantly affect surface strength of wood to be of practical use in preventing damage such as
denting, scratching etc.
Can't see that it would cause distortion of a lute bowl either.
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