Homebrew natural wood stains #1: essential oils distillation apparatus

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Blog entry by Sodabowski posted 05-12-2015 07:51 PM 2378 reads 0 times favorited 4 comments Add to Favorites Watch
no previous part Part 1 of Homebrew natural wood stains series Part 2: tea and iron acetate, aka ebonizing wood with vinegar »

Hi all,

In this series I will showcase some hardware stuff I will build along the way to produce my own natural wood stains.
Having pursued that Masters Degree in Physics AND Chemistry enabled me to dig rather deep into the mechanisms behind color and the different processes and whatnots that are best to know in order to get the results wanted.

In this first installment, I’ll show the making of a very crude but definitely functional Liebig condenser, from off-the-shelf components, ie plumbing copper adapters and tubing.

First, a word of information: in order to extract essential oils from natural products, you have to boil them and recondense the vapors to recover the oils. For that purpose, you need a water-circulating condenser, of which several kinds exist. Usually for distillation the Liebig is used, sinde it’s both the simplest and the only one with a straight path from input to output, which allows for an almost continuous flow of recondensed vapors. Here is the working principle of the apparatus:

The boiler I will use is a standard kitchen pressure cooker, the only modification that the model mom gave me was that it had a pre-boiling safety lock, which needed the pressure to rise to 0,4 atm, resulting in a complete disaster when it comes to distillation (everything would escape before the safety engaged). So I modified it simply by moving the rubber seal on that valve to keep it permanently closed, in an easy reversible manner. Not all pressure cookers have that feature so I won’t go more into details. All you really need is an airtight lid with a hope and a hose to feed your condenser.

So here are the steps of the build of the Liebig:

two copper couplings are soldered together to get the proper reduction: ID of the smallest is the OD of the feed-through tube, OD of the biggest is the diameter of the big tubes for the outer jacket. The cold water will flow around the feed-through tube and inside the outer jacket, resulting in a constantly cooled surface against which the vapors will recondense and flow down into the output container.
A pair of these are made, one for each end of the feed-through tube.

The outer tube is soldered, one side at a time. Here I used copper rings that are normally used to solder two lenths of tube together, since I didn’t find the bigger diameter tube.

Afterwards, the brass hoses are soldered perpendicular to the outer jacket. The holes will be drilled through them after they’re soldered, otherwise the operation is uselessly complicated. I only rounded the bottom of each hose to get the proper radius over the outer tube.
This is where it became messy and tricky as hell, and I stopped taking pictures. The brass melts at a way lower temperature than pure copper, so I had a lot of trouble (holes melting into the hose, bad solder fluxing, solder bubbling). I eventually managed to have everything properly soldered.

After the hoses were soldered, I drilled through them to puncture the outer jacket, then added the feed-through inner tube and soldered it in place. Once everything was done, I added another barbed hose to one side, which thus became the input of the condenser, heated and shaped the feed-through inner tube, then it was onto the brushing station to get it clean. Hot soapy water and a rotary steel brush gave it a proper cleanup.

And here’s the finished Liebig Condenser it all its glory.

Next up was building a stand for it, and since we had a full 50 Litre barrel of cider to process (not enough sugar for a proper cider, but man, did those yeasts produce alcohol!) I made a quick-slap plywood stand, with a length of copper tube as a vertical stand.

And here is the finished apparatus, fitted to the pressure cooker. It took us three full days to process the full load of the cider barrel, which ended up as three and a half liters of pure apple alcohol. After an initial run that helped fix several soldering problems (water dripping out of the outer jacket) it performed flawlessly. Not bad for starters, since I had been wanting to build my very own Liebig condenser for almost twenty years.

I do have a lab setup that I already posted here, but the problems are that:
  • you can only put that much stuff in the round flask (200 mL in mine) , and
  • said stuff has to be ground down with water for you to be able to feed it inside said round flask.

With the pressure cooker, no problem: you just fill the stuff to half its height, put the lid on, and you’re ready to go.

Now that I had that thing sorted out, next time I will be able to use that setup for boiling tinctorial plants. The South-West of France was famed for its Pastel factories back in the Middle-Ages, so we have a LOT of that Isatis tinctoria thingie around. My plan is to make my own indigo pigment, among others, to stain shop-sawn veneers. Other species that we have around carry Berberine, the yellow molecule produced by barberries (barberry root is the yellowest wood you will ever come across, and it was used intensively for marquetry back in the day). Since the real thing is REALLY difficult to come across in the wild, my plan is to use the natural molecule to stain holly veneer (from the family forest stands) to get me some decent yet natural yellow veneer.

All questions welcome! Cheers.

-- Thomas - there are no problems, there are only solutions.

4 comments so far

View shipwright's profile


8780 posts in 4128 days

#1 posted 05-12-2015 11:32 PM

Hi Thomas. I love this. (You’re really a rubbish plumber but a fine scholar.). :-)
I will be following with bated breath and humbly offer my services for any field testing you may require.
I would love to be able to recreate the barberry yellow and some of the greens and blues of the Sun King’s day.
Will you be doing penetration tests on other media (bone for example)?
Keep in touch. I hope to be back in Paris in the fall of 2016. See you then. I’ll buy the kebabs. :-)

-- Paul M ..............the early bird may get the worm but it’s the second mouse that gets the cheese!

View Sodabowski's profile


2401 posts in 4163 days

#2 posted 05-13-2015 09:34 AM

Hi Paul. Yeah, I really need a proper soldering flux, pure borax doesn’t do the cut for plumbing, hahaha.
I’ll absolutely be doing staining on bone and wood, although I’ve seen by field testing that pure ethanol partly destroys bone, so I’ll have to find another solvent that both carries the Barberine properly and doesn’t damage bone (acetone probably).
Man, fall 2016 sounds far enough for me to graduate and set enough cash aside for both the kebabs and a pretty decent load of rosewood :D

-- Thomas - there are no problems, there are only solutions.

View Schwieb's profile


1922 posts in 4791 days

#3 posted 05-13-2015 10:36 AM

Hi again Thomas, Paul already beat me to the soldering /plumber comments, LOL I commend you for taking on this more scientific aspect of woodworking. I still remember your work on spalting, etc. Looking forward to seeing more of this from you.

-- Dr. Ken, Florida - Durch harte arbeit werden Träume wahr.

View Sodabowski's profile


2401 posts in 4163 days

#4 posted 05-31-2015 09:28 AM

Well, I settled with bronze solder on this one, so I had to heat it BIG TIME (with the oxygas torch) to get it hot enough. After the fact, I fixed the minute dripping flaws with tin solder, which requires a far lower temperature at which the copper doesn’t oxidize. I also had to deal with soldering the brass barbed hoses to the copper tubes, which would have been too weak in my own taste. Nonetheless I have a rock-solid Liebig condenser now, and it has already seen a LOT of use, almost weekly!
I’m certainly not done with spalting, I have plans for something to try this summer (that is, if I find the little sap sugars suckers in good shape!).

-- Thomas - there are no problems, there are only solutions.

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