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jdowning
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What's Cooking? Egg White Varnish.
That culinary delight - meringue - is, on the face of it, a simple enough concoction of egg white and sugar. However, as no doubt as many a 'would be'
chef will admit, making meringue is not as easy as it might first appear.
The crucial part of the recipe is that of beating egg white with a whisk for several minutes until it forms a stiff stable foam after which sugar is
then added to 'fix' the foam prior to baking in an oven. There are many factors affecting successful formation of the foam including temperature,
humidity, surface tension of the egg white, type of mixing utensil, age of the egg, time of year the egg was laid, type of whisk or beater, duration
of whisking, bubble size etc. Above all the mixing vessel and whisk must be completely dry and totally free of any traces of oil or fat (such as egg
yolk or oils from fingers) that will prevent formation of the foam bubbles.
The foam is created due to the mechanical action of the whisk that alters the molecules of the albumen protein so that they solidify around air
bubbles also created by the whisking action.
For meringue, beating continues until the foam is very stiff but still slightly moist (when the mixing bowl is inverted the foam will not fall out).
At this stage, if the foam is left to stand a watery fluid will slowly accumulate at the bottom of the mixing bowl under the foam.
Whisking beyond this point causes the foam to become dry and hard - useless for cooking or any other purposes.
So - why all this talk about successfully making egg white foam? What does this have anything to do with preparing an egg white sealer or varnish?
Cennino d'Andrea Cennini wrote his little book "Il Libro dell' Arte' during the 15th C in Florence, Italy. It contains recipes, procedures and other
guidance that was of interest and practical value to painters, sculptors and other artists of his time. (A modern translation of the book is available
from Dover Publications, New York as "The Craftsman's Handbook").
In a chapter on varnishing Cennini describes how to quickly make carvings look as though they were varnished (but without having to use an oil
varnish).
To prepare the "varnish", the white of an egg is beaten as thoroughly as possible with a whisk so that it forms "a good, solid foam". The foam is then
left to "distil" overnight. The part that has distilled (i.e. the watery fluid in the bottom of the mixing bowl) is then applied to the work with a
"minerva" brush. (a minerva brush is a soft varnish brush made from the hair of an ermine or weasel). Cennini concludes this brief instruction by
commenting that the carvings of either wood or stone will look as though they were varnished and will be stronger.
(Cennini makes no mention of this treatment as being suitable for finishing lute sound boards - although he does recommend glue formulas for the
making and repair of lutes. This, of course, does not mean that egg white was never used as a sound board finish in earlier times).
Clearly the Cennini's initial step of first whisking the egg white to a solid foam and using only the distilled fluid had some significance - the
fluid perhaps having a different molecular structure than raw egg white.
So are those who today, in good faith, apply raw egg white to their sound boards missing a key step in preparation of the albumen?
Perhaps it would be a good idea to first spend some time in the kitchen making a few meringue pies - in order to learn how best to prepare and handle
egg white - before applying it to the sound board of an instrument.
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FastForward
Oud Junkie
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Thanks John, this is fascinating. Like you said, the description is unlike what most people do when they apply the egg white to soundboards.
Anyway, I will probably keep the Meringue away from my oud. I will probably use a 1/2lb or 1lb cut of shellac to apply a very thin sealer coat on the
oud I am making.
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SamirCanada
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Great find John!
Thanks for sharing.
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jdowning
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I should add that - out of curiosity - I did a quick test using, for convenience, some supermarket egg white that happened to be in the 'fridge' -
just to get a feel for the possibilities (this stuff has likely been subject to pasteurisation so is not to be recommended in place of 'fresh' egg
albumen). The humidity levels are here quite high at present (an environment not recommended for beating egg white). Nevertheless, a fairly 'soft'
foam was the result and so the 'distillate' from this was brushed on to a test piece of Canadian 'silver spruce' soundboard wood using a soft Chinese
white goat bristle brush (too soft for applying an oil varnish). The watery consistency distillate fluid was immediately absorbed into the wood
(without any sign of brush marks) and appeared to dry quite quickly (within an hour) with minimal (if any) raising of the wood grain - although, not
surprisingly, some permanent darkening of the wood was apparent.
A further test using the white of a whole egg (Omega 3 - is this better than a good, old fashioned, free range 'farm' egg?) will be undertaken once
humidity levels drop to a more comfortable level.
Of course - historically -' the jury is still out' on whether or not some kind of 'invisible' sound board finish was ever applied to lutes or ouds.
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jdowning
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Clearly your comments expressed here about turpentine have no relevance to this topic fernandraynaud.
If you want to experiment with and discuss the possibilities of mixing turpentine (or other oils) to egg white in an effort to make a sound board
finish other than one made from unadulterated egg white, then you should do so on one of the two current topics that you have already created on this
forum i.e. "Soundboard/face protection" or "Finishing the face with Egg White" - or create a new topic dealing specifically with your interest and
concerns in oil varnish components.
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jdowning
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Thanks for removing your postings fernandraynaud.
Good luck with your alternative sound board finish experiments.
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jdowning
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In an effort to try to understand what Cennini's egg white 'distillate' might consist of, some recent scientific work on egg white (albumin) foam
stability has been consulted. An understanding of the properties of albumin foams is of commercial interest to the food industry so the results of
much of the work done in this field is not freely accessible (and, in any case, is likely not readily understood by those of us who are not
microbiologists).
However, some papers reporting the results of experimental investigations into albumin foam stability do appear to provide some information that may
be of interest here. The stability of the foam in these investigations was assessed by measuring foam drainage volume and its chemical analysis (i.e.
Cennini's 'distillate') against beating time.
Raw egg white is made up of water and about 40 different proteins. The proteins each have a long chain molecular structure and in the unmodified
albumen just lie around curled up in a random mass - like a tangled ball of string. The proteins are of two types - those that are attracted to water
(hydrophilic) and those that are repelled by water (hydrophobic).
When raw egg white is whipped or beaten, the mechanical action of the beater causes the albumen to change from its natural state at a molecular level
(denaturation). The beating action also forms air bubbles. The denatured proteins unravel and bond together at the air/water interfaces forming a film
around the air bubbles to produce a foam.
The stability of an otherwise untreated albumin foam depends upon the level of denaturation of the protein molecules and bubble size (as well as the
presence of any foam destabilising agents such as fats or moisture). As beating time is increased, the air bubbles increase in number and decrease in
size creating a drier more stable foam. Excessive beating eventually causes the protein to coagulate into a hard foam devoid of fluid.
If a 'soft foam' (large air bubbles, lightly whipped) is left to stand, the foam will mostly break down into a watery 'distillate' like the original
egg white whereas a more stable stiff foam (formed by beating the egg white for several minutes) results in a much lower volume of 'distillate'.
Cennini instructs that the egg white be " beaten as thoroughly as possible so that it comes out a good solid foam" So it is the the properties of an
egg white foam beaten almost to the denaturation limit that is of interest here.
Let's now look at the experimental results reported by some researchers in this field of investigation.
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SamirCanada
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Great research John,
thanks for contributing as I am anticipating to treat my next soundboard with this type of egg sealant formula.
Btw, will you be attending the Glengarry wood fair?
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freya
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Just as a point of information, and the sample size is not large enough to be meaningful, the top of the one oud where I tried the egg-white finish
cracked a few weeks after the egg-white was applied. This was in the late Spring and the RH was back up in the 60s so I don't think dryness was an
issue - the top had made it through the previous Winter just fine. I would have dismissed this as a fluke but I spoke about this to a well-known oud
maker who said the same thing had happened to him and he would not use egg-white again as a result. I don't want to suggest any causality here, just
giving two, possibly meaningless, data points.
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jdowning
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Thanks for that piece of information Harry. Was it raw egg white that caused the problem?
I shall eventually be testing the 'Cennini egg white foam distillate' on sound board test pieces in order to better understand the properties of the
distillate once dried so may be able to confirm if cracking is a potential problem.
So far I have not been able to verify if egg white raw or in any formulation was ever used as a sound board finish historically.
Humidity is still very high here at present so preparation of the 'distillate' will have to be postponed for the time being.
I will not be attending the Glengarry Wood Fair Samir as I am scheduled to present a workshop (talk/recital) at one of the other local museums on that
day (21 August at 2 pm).
The title of the workshop is "A Renaissance of the Lute" covering (briefly!) the development of the lute and its music in 16th C Europe.
The museum is the historic Macdonnel-Williamson House located at Pointe Fortune by the Chute-a-Blondeau - a rural setting near the Ontario/Quebec
border. Admission free.
http://www.mwhouse.ca/news_events.html
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freya
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Hello John,
I just separated the yolk and the white and brushed the white onto the face - no heating or whipping. Though I think my wife used the yolk to make a
tasty coffee cake afterward...
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jdowning
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Ah! One of the benefits of this line of investigation!
The food industry has a commercial interest in being able to manufacture baked goods of consistent quality. Research into the properties of egg white
foam in particular has, therefore, focussed in part on investigating how to produce the maximum volume of stable foam as well as assessing the food
value of the resultant foam. It has been found that the length of time that egg white is beaten or whisked is a critical factor. The volume of
drainage ("distillate") from egg white foam has also been used by investigators as an indicator in measuring foam volume, foam stability and the level
of denaturing of the foam.
For those who are interested in experimenting with egg white foam "distillate" as a sound board sealer here is a brief summary of the findings of
some of the food industry researchers - information that may be of some relevance.
- Egg white must be separated from a whole egg.
Commercially prepared egg whites do not foam well for two reasons - it is not possible to completely eliminate traces of egg yolk from commercially
prepared egg white (the fat in the yolk prevents foaming) and the egg whites are sterilised (pasteurised at 53 C)) with heat which causes partial
denaturation of the protein reducing foaming ability.
- All equipment used to prepare the foam must be completely free of traces of oil or grease. Do not use plastic bowls or utensils - plastic retains
oils and grease.
- moisture in the atmosphere has a negative effect on foam production. Do not beat egg whites when there is rain in the forecast or humidity levels
are high.
- egg white produces foam more quickly at room temperature rather than cooler refrigeration temperatures (surface tension is less at room
temperature).
- the optimum time of beating to produce a foam of maximum volume and stability is about 7 minutes (determined experimentally by measuring drainage
volume). Beating beyond this point results in extensive coagulation of the foam decreasing its water holding capacity and hence increasing drainage
volume. Beating for a shorter period of time produces a lower volume, coarser foam that is less stable allowing both unbeaten egg white and the foam
films to drain away as increased drainage.
- drainage from 'over beaten' foam is of lower viscosity (up to 50% lower) than that of the raw egg white (i.e. is more 'watery') and pH value
increases up to 9.3 (i.e. is more alkaline).
- the foam drainage contains diminished levels of protein (dependent upon beating time).
- The age of an egg is of no consequence when beating periods of over 4 minutes are involved.
Unfortunately the food industry researchers have no interest in the properties of foam drainage once it has dried out. That is for those of us
interested in the possibility of using the material as a wood sealer to discover by testing.
One question to resolve is for what period of time did Cennini beat his egg white to produce "a good solid foam"? Clearly the chemical composition and
hence properties of the "distillate" collected and used as a "varnish" for wood critically depends on this. Perhaps the first attempt to replicate
Cennini's instructions should be to beat the egg white for 7 minutes?
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jdowning
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Question - is dried egg white "varnish" water resistant (if not fully waterproof)?
Henley's 20th C Book of Formulas, Processes and Trade Secrets describes an 'Albumen Paste' as follows :
"Fresh egg albumen is recommended as a paste for affixing labels on bottles. It is said that labels put on with this substance, and well dried at the
time, will not loosen even when bottles are put into water and left there for some time. Albumen, dry, is almost proof against molds or ferments."
So this might be confirmation that dried albumen is not only water resistant but resistant to decay. Testing required!
Cennini refers to the application of egg white 'distillate' on wood or stone (or a painting) as "How to make a Painting look as if it were Varnished.
In order to give one of your works the appearance of being varnished within a short time, without it actually being so ..."
An "appearance of being varnished" presumably means that - after an application (or several applications?) of the egg white 'distillate' - the surface
will be 'glossy' in appearance?
Cennini implies that the 'distillate' should be used as soon as it has formed 'overnight'. However, what if the 'distillate' was not used immediately
but left to concentrate (by evaporation) for several days before application? A sample of my supermarket egg whites has been left exposed to the
atmosphere now for over 10 days and is gradually drying up and becoming thicker and more viscous. This 'concentrated' material will now be applied to
a sound board test strip to check if it performs like a varnish and the remainder will be allowed to fully dessicate (dry out) to see if it can then
be dissolved in water - as a test of its water resistance.
It is interesting to note that the medical profession is using 'purified' (?) albumen to repair or seal holes or tears in membranes. One source
reports that even small holes in balloons may be successfully sealed with albumen. So, although when dried, albumen appears to be quite brittle, it
must have some residual flexibility and strength - not to mention resistance to fluid penetration (water included).
Interesting stuff!
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fernandraynaud
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What I can contribute is that I am certain that my egg white is NOT waterproof. I applied 4 coats of plain unwhipped albumen, sanding
between coats. If the albumen builds up thicker, it polishes to a nice (but fragile) satin gloss. Or you can sand it down further and the spruce looks
almost untreated. I did one soundboard more glossy, and one more matte. The "dust" on the plastic steel wool has a white flaky appearance.
It happens that I literally drooled a drop on the more glossy soundboard, undoubtedly from a sense of awe. The saliva penetrated, dissolved in the
albumen; there was nothing to blot up. The next day it was difficult to buff it back to its previous state, as the top glossy layer had been reduced
on the area, presumably wicked into the wood. If it had been wine or coffee, I believe the water would have transported an ugly stain deep into the
wood. John, I would be surprised if your "distillate" somehow became water-resistant by evaporation. I can believe that albumen would make
labels adhere by occupying the gap and not "floating away" even if wet.
My question was simply what to use on soundboards. One value of egg-white coating is that it's a bit of a barrier to dirt; if nothing else
you can make a pass with fine steel wool and clean the soundboard that way, maybe reapply some egg white. It doesn't impart a yellowish hue. But
compared to shellac, which is both waterproof and resistant to lipids, I'd say it's vastly inferior as a soundboard coating. I'm very curious what you
will come up with.
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jdowning
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I also am curious to find out if egg white might have properties that make it a suitable finish for sound boards - so will pursue this investigation a
bit further, with an open mind - in order to at least satisfy my curiosity. Note that I am not advocating egg white as a sound board finish and have
yet to find any evidence whatsoever that egg white was ever applied historically to either oud or lute sound boards (but oil varnishes or shellac
finishes certainly were not).
The vastly superior historical finish would, at the present time, appear to be - none!
I do not doubt that dried albumen is not completely waterproof like a varnish finish may be but I would expect the optimum foam distillate to have
some water resistance - yet to be confirmed by testing. In any case, what is supposed to be the virtue of a waterproof soundboard finish - apart from
providing some protection against gross abuse of an instrument?
BTW it is not 'my distillate' - I am simply trying to make sense of the historical information recorded by Cennini. Note that Cennini did not state
that this finish was suitable for lute sound boards either.
I became interested in this topic as a result of your question in another thread (that, for some unknown reason, promptly 'ground to a halt') which
was not simply 'what finish to use on sound boards' but more specifically "Has anyone applied egg white and then applied shellac/French polish"
The answer to that would seem to be 'yes'.
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fernandraynaud
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Is everybody a little nervous today? I'm not in any way denigrating "your distillate" or your approach. I'm not accusing you of anything. I was just
passing on my accidental experiment specifically related to your topic, namely whether egg white can make a suitable coating for soundboards.
Personally, yes, I see value in a coating that resists soiling.
My question thread, that you apparently consider flawed enough to comment on, logically stopped when you very kindly answered my question, pointing me
towards people who use egg white as a sealer.
Though I don't understand what I've done to make you angry, I certainly didn't intend to.
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jdowning
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I am not nervous or angry and was otherwise unware that you were accusing me of anything fernandraynaud.
BTW the topic of this thread is concerned with investigating the properties of the drainage (or distillate) from egg white foam - not those of raw egg
white - and the possible suitability of the distillate (not raw egg white) as a sound board sealer.
Researchers investigating properties of egg white foam and foam drainage have confirmed that at 'optimum' foam volume, the drainage collected contains
lower percentages of the protein content than raw egg white, is more alkaline and of lower viscosity. Also reported is that many of the denatured
protein structures have irreversibly changed characterised by the presence of sulphur atoms (sulfhydryl and disulphide) that apparently do not occur
in the raw egg albumin. Whether or not this will have any significant bearing on the properties of the distllate, once applied to wood and allowed to
dry, remains to be seen.
Those properties (hopefully) will be determined by, albeit low tech., experimental application.
The high humidity levels are starting to drop so there may be an opportunity soon to prepare the first experimental batch of egg white distillate for
testing.
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jdowning
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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.
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jdowning
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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.
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jdowning
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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.
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fernandraynaud
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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.
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jdowning
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Your current experiences with raw egg white as a sound board finish/sealer are not relevant to this thread fernandraynaud!
Why not post them on either of your current topics "Soundboard/face protection" or "Finishing the face with Egg White" where they would not be out of
place?
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fernandraynaud
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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?
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jdowning
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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.
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jdowning
Oud Junkie
Posts: 3485
Registered: 8-2-2006
Location: Ontario, Canada
Member Is Offline
Mood: No Mood
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It is apparent from tests carried out so far that egg white foam distillate is quite different from raw egg white - although I do not pretend to
understand what has happened in the transformation at a molecular level or what the chemical analysis of the distillate might be.
I had eggs for breakfast so was able to test the pH level of the albumen before it was denatured by heat (i.e. cooked). An indicator strip showed a pH
value of 8 which agrees with values given in tables recording the pH values of common household materials (pH range for egg whites 7.6 to 8.0).
The pH scale is logarithmic (base 10) with neutral value (pure water) of 7.0.
So if the indicated pH value of 10 for the distillate that was measured the other day is representative, that means the distillate is 100 times more
alkaline than raw egg white.
When the distillate is applied to the test piece it is absorbed by the wood more quickly than water indicating that the distillate has a lower
viscosity (and surface tension?) than plain water.
Also the distillate which is quite transparent - when dried - permanently darkens the wood whereas plain water does not.
Cennini notes that his distillate not only gives work (wood, stone, paintings) the appearance of being varnished (darkened surface?) but also gives
the work added strength. This all suggests that there may be some kind of chemical reaction occurring between the distillate and the wood itself.
Tests carried out on hardwoods some time ago on this forum (see the 'marinated' wood topic) indicate that alkali solutions (such as diluted household
ammonia) react chemically with the wood cell structure as well as dissolving extractives within the cells (dependent upon the length of time wood is
immersed in the alkali solution). Softwoods were not tested as part of that investigation, however.
Household ammonia has a pH value of about 11.0 so is 10X more alkaline than the egg white foam distillate. To investigate if alkaline solutions do
react with softwood - perhaps partially dissolving the resins in the wood - a preliminary trial will be to 'varnish' the untreated surface of the test
piece with dilute ammonia, allow to dry and then compare the results with those already obtained for the distillate coating.
A further investigative step will then be to immerse a sample of softwood in the distillate for an extended period of time - just to see what
happens.
The sample of distillate that has already been set aside to dry into a solid residue (for solubility testing) will be regularly checked for pH value
as it (slowly) dries up and becomes more concentrated. So far there has been no detectable increase in alkalinity - although the pH test strips only
measure in unit steps so can only give an approximate indication of pH value.
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