What's Cooking? Egg White Varnish.

There has been a brief drop in humidity levels so the opportunity was taken to prepare batch #1 of egg white foam distillate for testing.
Two large Omega 3 (low cholesterol yokes) were selected and the egg whites were separated from the yokes into a grease free bowl while still at refrigerator temperature (easier to separate than at room temperature).
Unfortunately the yolk on the second egg broke and a small amount spilled into the separated egg white. This was removed with a clean spoon but as it is not certain that every trace of yolk was removed the test will be repeated at a later date with another batch of egg white.

The egg whites were beaten for 7 minutes with an electric powered whisk running at half speed. This was sufficient to form a stiff foam which was then left overnight. After 14 hours the foam had become lighter in texture (more like a detergent foam) and 15 ml of 'distillate' had collected in the bottom of the bowl. This is batch #1

Conditions when egg white beaten - temp. 22 Celsius, 63% RH
Conditions after 14 hours - temp 20 Celsius, 69% RH.

The distillate was clear with slight yellow tint and viscosity like that of water. The alkalinity was measured at between pH 9 and pH 10 using litmus test papers (this agrees with the findings of other researchers). The alkalinity of the raw egg white prior to beating was not tested.

A test piece of fine grained quarter sawn silver spruce, planed smooth, was then coated with the distillate - applied with a soft brush - until the surface of the test piece was 'flooded'. The distillate was immediately absorbed by the test piece which was then left to dry for 24 hours.

The dried test piece surface was then 'polished' to a light sheen with a piece of fine cotton cloth.

To test the dried 'distillate' for fluid resistance, a drop of water was allowed to remain on the surface for 60 seconds, then blotted with a paper towel and allowed to air dry. There was no obvious sign that the dried distillate had dissolved or allowed the water to penetrate the wood surface.
The test was repeated using a drop of red wine. Again none of the fluid was seen to have penetrated or stained the surface.

So from these two tests it would appear that a single coat of distillate - once dried - offers at least some level of water resistance and protection from staining.
This should be sufficient time for a conscientious oud owner to immediately mop up any accidental fluid spills from a sound board to avoid any residual marks or staining. Of course drinking and oud playing together is a practice not to be recommended!

Now to run a more extended test with water.

This time the drop of water was allowed to remain on the surface for over an hour (65 minutes to be exact) before being blotted and allowed to air dry. Note that after an hour the water droplet has diminished in size but has not spread in area - indicating that some surface evaporation of the water has taken place.
Under magnification (10X) a very faint white outline of part of the water droplet edge could be seen on the surface of the test piece. However, this could be polished away with a cotton cloth becoming invisible - indicating that there perhaps may have been some slight dissolving of the 'distillate' sealer. On the other hand, the water droplet was tap water that in this area is 'hard' containing calcium - so the 'white outline' may just be traces of calcium deposits remaining after the water had evaporated and dried?

The test piece has now been given a second coat of 'distillate' over the first. The second coat appears to have been absorbed by the test piece and so will be allowed to dry for 24 hours before repeating the droplet test.

Note the darkening of the surface of the test piece following application and drying of the 'distillate.

This is really quite interesting. So something significantly changes at the molecular level as it sets, some sort of polymerization, since I assume the solution is still mater-miscible. Is your wood as porous as typical soundboard?

Unseparated egg white behaves quite differently. I won't repeat your test with the wine, but you can see what happens to a layer of raw egg white. Aqueous solutions penetrate and dissolve the polished surface. It's barely visible unless you look at an angle to the light. It's easy to fix by applying some more, but of course it defeats the purpose, and any pigmented solution will have penetrated the wood. The virtue of plain egg white coating is also its weakness: it's unobtrusive, easily touched up and easily removed. What has penetrated the wood during treatment is probably entirely water, leaving the proteins as the fragile coating that buffs up so nicely.

Since you have the materials on hand, if you could try putting some unwhipped egg white on part of the other side of you board, let it dry or blow-dry it, then see how the distillate interacts with it, it would be very helpful, as in light of your discovery that may be a better next step on these soundboards than French polishing, for those of us who went with the plain egg white.

Please be nice, current scientific thinking is that making fellow-patients feel bad is not therapeutic.

In my view what I posted is on-topic enough. But if this is "your" thread, is this any way to treat guests? If you consider threads to be private property, you logically should have stayed out of mine.



Returning to the thread, I was wondering if the distillate is still fully water-miscible, and if your test wood is as porous as typical soundboards. And is there any chance you would be so kind as to try distillate on top of raw egg white?

Really?!

Regardless of what you want to believe fernandraynaud, the image that you posted of your oud with its failed raw egg white coating is not relevant to this thread and neither is your question about any interaction there might be between dried raw egg white and foam 'distillate' although these might not be out of place on your thread "Finishing the face with Egg White" that seems to have ground to a halt (?).
If you want to determine how egg white foam distillate reacts with the dried raw egg white coating on your ouds why don't you just go ahead and prepare some 'distillate' as demonstrated earlier in this thread, run some tests yourself and report the results on your thread "Finishing the face with Egg White"? You might then also end up with some first hand experience about preparing the distillate that could be of enough interest and relevance to report on this thread.

When you ask "if the distillate is still fully water-miscible" I take it that you mean compared to raw egg white (both being in the liquid state)?
If I add water to the distillate a small quantity of a white sticky film forms on the surface - an indication perhaps that the distillate is not fully water-miscible.

However, as Cennini makes no mention of diluting the distillate with water prior to its application then this is of little interest here.
Nevertheless, I am interested as to whether or not the dried residue of the distillate is soluble in water so currently have a small sample - set aside two days ago - to air dry (slow).

On the question of the porosity of the wood sample, I previously reported that the first application of the distillate was immediately absorbed into the wood.
The sample is very fine grained, quarter sawn 'Silver Spruce' set aside about 20 years ago as a promising looking sound board wood. 'Silver Spruce' is a generic term used by the timber industry that might apply to any of the North American spruce varieties such as Sitka Spruce, Engelman Spruce, Colorado Spruce etc.

For information and comparison the attached image shows the appearance of absorption of a water droplet on the untreated surface of the 'Silver Spruce' sample as well as on a sample of 'Sitka Spruce' sound board material - after about a minute.

The test piece moistened with household ammonia solution has been allowed to dry overnight. The dried surface offered no resistance to the water droplet test so the brief exposure of the wood to the alkaline solution (before evaporating) was not sufficient to significantly affect the wood cell structure or dissolve the resins to form a water resistant coating.

The test piece with two coatings of distillate showed the same level of resistance as the single coating in the water droplet test. In this test a water droplet was allowed to remain on the surface until fully evaporated (3 hours) and left a visible 'ring' or watermark that did not polish out with a cloth. The attached macro image shows the 3hr residue next to the faint white residue left after a water droplet had remained on the surface for 60 minutes, blotted and then allowed to dry.

A small sample (2.5 ml) of batch #1 of the egg white foam distillate had been set aside for a few days to completely evaporate.

The resultant residue remaining in the bottom of the measuring cup was clear and transparent with a very slight yellow tint. The dried residue was brittle.
Water (2.5 ml) was then added to the residue which immediately started to dissolve (like a gum) becoming fully dissolved with stirring in about 5 minutes. The resultant fluid was clear and transparent with a slight yellow tint and tested at about pH 10 alkalinity.
The residue is therefore fully miscible in water and appears to have the same properties (?) as the original distillate when reconstituted.

The reconstituted distillate will again be left to fully evaporate - just to see what happens.

This morning - after a period of 48 hours - the 'reconstituted' foam distillate residue, set aside to evaporate, had a slightly cloudy appearance due to the presence of a lot of small particulate matter in suspension. So far there appears to be very little - if any - fluid lost due to evaporation.

The fluid was examined under high magnification (X450) using a laboratory standard microscope. This revealed - apart from a few larger visible particles of what seemed to be distillate residue (transparent, light yellow tinted) - a mass of microscopic particles of the same material (transparent, light yellow tinted) in suspension, so small as to be invisible to the naked eye.

Hard to know what is going on here but it would seem that the addition of a relatively large volume of water to 'dissolve' the dried distillate residue caused the residue - initially - to break up into minute fragments (molecular sized?) that then begin to rejoin together (by molecular attraction?) over time into increasingly larger sized particles of the residue.
In order to test if the particles are joining together by some kind of molecular attraction and not as a result of fluid evaporation, water will be added to the sample daily to compensate for any evaporation losses.

The microscope is an old but high optical quality Leitz compound microscope. It took a bit of adjustment to obtain the best light contrast to show up the particles.
The attached images were taken with a Canon Powershot A470 digital camera, in 'point and shoot' mode, simply held over the eyepiece of the microscope - hence the 'vignetting'. All a bit 'rough and ready' but it worked well enough to give a reasonable appreciation of what could be seen under the microscope.

With sufficient quantity of batch #2 distillate available samples of silver spruce have been prepared and left to soak in the distillate in a sealed container. This test is to find out if there might be a reaction between the alkaline distillate and the wood.
After 24 hours immersion of the wood samples, the distillate had darkened in colour from the pale lemon of the distillate to a light brown tint that appeared to be slightly cloudy. Small bubbles of gas (air?) could be seen coming from the wood samples forming larger, stable bubbles on the surface of the distillate.
Microscopic examination showed that the cloudiness is due to many solid particles in suspension. The particles have a random shape and lemon yellow tint looking very much like the distillate residue particles in the microscopic images previously posted.

This morning (three days later) the surface bubbles have reduced in size and quantity and emmission of bubbles from the samples seems to have ceased. This may indicate complete saturation of the samples with the didtillate.
The distillate is now full of particles - visible to the naked eye - giving the distillate a clouded appearance.

Here are the images missing from the previous posting

The wood sample will be left soaking in the distillate in order to see how the wood is affected by the alkalinity of the distillate.

As a further test - for purposes of comparison - samples of silver spruce and sitka spruce have been allowed to soak in household ammonia solution in sealed containers. Household ammonia is a 5% solution of ammonia in water with a pH value of about 11. The greater alkalinity should, therefore, accelerate the test into a shorter time period than for the distillate.
After soaking for 24 hours in the clear ammonia solution the solution in the silver spruce container had changed to a clear wine red colour and that of the sitka spruce to a clear pale yellow colour. Clearly some kind of chemical reaction is in progress.

After 6 days immersion in Distillate #2, the silver spruce sample seems to be fully saturated. The distillate is 'muddy' in appearance due to the presence of many particles in suspension.
Under the microscope - in addition to larger particles of what seem to be distillate residue there are a number of 'tree like' growths (dendrites) where individual cells seem to be joining together into longer chains.
Not sure what to make of this at present - so just for the record and information.

Batch #2 foam distillate is being tested as a coating on a sample of quarter cut Sitka Spruce sound board wood. The distillate was brushed on so that the surface of the sample was 'flooded' and then allowed to dry for 24 hours. The distillate caused the wood to darken in colour and a distinct distillate residue accumulation was noted at the edge of the coated surface.
The coated surface was then tested for water resistance by allowing a large water droplet (11 mm diameter) to remain on the surface until completely evaporated (several hours). This left a ring of distillate residue at the perimeter of the droplet. The area inside the ring was paler in colour than the distillate coating outside
So it would appear that the water 'dissolved' the insoluble component of the dried distillate into smaller residue particles which then migrated (under surface tension?) to the outer edges of the water droplet.

The area within the ring of distillate residue appears to have been cleared of residue on the surface of the wood sample. Is this area water resistant due to a chemical reaction and/or molecular bonding between the distillate and the wood cells?

To answer this question a droplet of water was placed in the centre of the ring and allowed to remain for 15 minutes. It can be seen from the shape of the droplet that it is sitting upon an impervious surface (compare this to a water droplet on a waterproof plastic surface). After 15 minutes the droplet was removed by blotting with an absorbent paper towel. After all moisture had dried there was no visible evidence of any water staining by the droplet or absorption of moisture into the wood.

This confirms that the surface is at least water resistant due to the presence of distillate that has soaked into in the wood cells. So it would appear that after flooding the surface of the wood some distillate is absorbed into the wood cells sealing them against moisture absorption while the surplus distillate dries out on the surface of the wood as a 'varnish' layer that can be 'dissolved' by the addition of water.

The next test was to 'wash' the dried surface of the test piece - coated with distillate - with water. Water was brushed over an area of the test piece (measuring 30 mm X 60 mm) - flooding the surface - and then allowed to dry for 24 hours.
Even with an area of this size distillate residue was observed to accumulate around the edges of the 'washed' area.
Two water droplets were placed on the surface - a small droplet measuring about 4 mm in diameter and a larger drop measuring about 12 mm across.

After 90 minutes the small droplet was blotted with absorbent paper. There was no visible evidence of water stain or absorption by the wood.
The large drop was allowed to remain on the surface to partially evaporate for 7 hours before being blotted and dried. There was no visible evidence of the water being absorbed by the wood although there were some slight traces of distillate residue that had formed around the perimeter of the drop - presumably due to traces of distillate residue remaining on the surface after 'washing'.

Enlarging the macro images of the large drop revealed what appeared to be minute bubbles of a gas on the surface of the wood - presumably similar to the gas bubbles observed during the immersion test previously posted. Sign perhaps of a chemical reaction taking place within the wood cells?

The next trial will be to coat a larger test piece of Sitka Spruce with distillate followed by a water coating and buffing to remove any dried distillate residue remaining on the surface. Then to run the water droplet test again

After soaking in foam distillate for 7 days, the silver spruce samples have been removed and allowed to dry. The colour of the distillate has changed from a transparent pale lemon tint to a cloudy orange.

For information, bubbles initially forming on the surface of the distillate had remained stable for several days but eventually disappeared after 7 days. It is interesting to note that stable bubbles formed again on shaking the jar containing the distillate.
The microscopic 'tree like' dendritic cell formations previously reported may have appeared as a consequence of the break down of the bubbles - the dendrites being part of the molecular 'network' structure surrounding the air bubbles and giving the bubbles (foam) their stability. So it would seem that the property of the beaten and denatured egg white molecules to form a stable foam remains - to some extent - in the foam distillate.

No dimensional change is obvious in the dried test samples although there has been a distinct darkening in colour of the samples (as well as the distillate). This indicates that there has been some kind of reaction between the alkaline distillate and the wood cells.
Microscopic examination of the end grain of the wood samples was inconclusive in that did not reveal any obvious visible change in cell structure or dimensions.

Test samples of silver spruce and sitka spruce immersed in an even more alkaline 5% Ammonia solution for 10 days and allowed to dry showed no obvious dimensional change but both samples and ammonia solutions also had darkened in colour.

This completes the immersion testing.

Next to report on tests with larger samples of Sitka Spruce sound board material coated with egg white foam distillate.

A larger sample of Sitka Spruce, cut 'on the quarter' and scraped smooth, measures about 10 cm wide by 15 cm long by 2 mm thick.

This has been coated with batch #2 foam distillate brushed on like a varnish and allowed to dry for 24 hours followed by clean water brushed on and allowed to dry for 24 hours.
Note that the batch #2 distillate for the test has been kept in a sealed container at room temperature for 12 days with no sign of deterioration.

The immediate effect of coating the sample with distillate is that the sample distorts (bows) due to the expansion of the wood cells as they quickly absorb the distillate. The distortion is significant - about 4 mm over 10 cm. On a sound board, say, 30 cm wide this distortion would amount to 12 mm.
After drying for 24 hours the sample lost its distorted curve and became flat again.

Therefore, for anyone contemplating using egg white foam distillate as a sound board sealer this is something to be taken into account. An oud sound board is prevented from expanding across its width by the braces glued in place. So any expansion of the wood cells caused by absorption of the distillated must be temporarily accommodated by compression of the moist wood cell walls until all water has evaporated. If this is done slowly over 24 hours or so (i.e. in relatively high humidity conditions, say 70% RH +), then, perhaps, no permanent damage will result. However, if the drying is rapid (low humidity conditions, say 40% RH or so) then it is possible that shrinkage cracking may be a destructive consequence in a braced sound board.
Egg white foam distillate is not the same stuff as raw egg white but the cracking of sound boards coated with raw egg white - as previously reported by freya - may be due to a similar mechanism?

After the larger test piece had been coated with #2 distillate and allowed to dry a second coating of plain water again caused the test piece to temporarily distort into a curve before drying flat again after 24 hours.
The large water droplet test was then repeated. After 15 minutes a droplet (about 12 mm across) was blotted with a paper towel. Once any surface moisture had evaporated there was no visible evidence of the droplet remaining.
A droplet remaining on the surface for 3 hours was again blotted and allowed to dry. The area covered by the droplet became slightly white after drying.
After 8 hours, a water droplet was reduced in size (due to evaporation) but showed no signs of absorption into the wood surface.
After 24 hours the water droplet had completely evaporated leaving - the now familiar - ring of distillate residue defining the perimeter of the water droplet.

So, coating the Sitka Spruce sound board sample with egg white foam distillate caused a temporary distortion (bowing) of the sample. After drying for 24 hours the sample became flat again.
Then, after applying a brush coat of plain water, the sample became temporarily distorted but, after drying for 24 hours, the sample again became flat again.

Interesting in that the distillate coated sample does not allow penetration of water, even after 24 hours exposure, yet the distillate residue coating the surface of the wood sample - after all water content has evaporated - is itself readily 'soluble' in water.

To follow - I shall try to draw some kind of conclusion from these tests!

It is interesting to note that the bubbles or foam generated by shaking the #2 distillate (left after the immersion tests - previously reported) is still remains after 4 days - although somewhat reduced in quantity. This confirms that the egg white foam distillate retains the ability to form a relatively stable foam - the denatured, long chain protein molecules linking together in a network around air bubbles.
How might this interesting property of the distillate account for the apparent water resistance of a sound board material coated with distillate when the distillate residue - when dried - is 'soluble' in water?
Time to speculate.

For comparison, the Sitka spruce wood samples were tested in order to determine if the egg white foam distillate is as effective a sealer for varnish as it is for water.

For the first test a drop of relatively 'thick' (viscous) oil varnish was applied to an untreated wood sample and to one coated with distillate. After 24 hours there was little evidence of any absorption of the varnish in either case - i.e. the varnish remained as a surface coating. The drops when dried measured about 3 cm. across in each case
A second test was to apply a drop of 'thin' (low viscosity) varnish (Minwax Antique Oil) to the wood samples. The oil finish quickly spread (in a matter of minutes) across the surface of both samples to cover an area measuring about
7 cm across in each case after the oil had dried. On examination, the oil had been fully absorbed into the wood on the untreated sample (leaving a dull 'matt' finish) but remained on the surface of the treated sample (glossy, 'varnished finish).

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.