How to make a pot still
Likely the simplest and most versatile distillation apparatus that one can make at home, is a pot still.
With a pot still one can
- Distill essential oils from aromatic herbs, flowers and seeds, oleo-resins like Frankincense, Myrrh, Pine and Spruce via hydro or steam distillation.
- Make grappa or moonshine from wine, mash or other fermented materials.
- Rectify and refine alcohol for medicine, perfume and liquors.
- Distill and purify water.
The process of distillation is grounded in nature’s basic laws, simple and almost archetypal, lending itself easily to metaphor and myth, to allegories of purification, transformation, transcendence, and spiritual refinement. Through familiarity with the process of distillation, one can understand many of the old symbols, sigils, allegories and metaphors of the ancients.
The “Art of distillation” is at the core of all alchemical traditions. It is the method by which the “subtle is separated from the gross”, and the process through with it is “married” back into its purified body and exalted at a higher vibratory rate. Modern chemistry owes much of its basic principles and processes, including distillation, to the ancient science and art of Alchemy.
The apparatus for distillation is often called a “distillation train”, and is made up of 3 fundamental parts, each performing a separate function.
- The first is the pot, flask, retort or boiler, which with the aid of a heat source, evaporates and separates the volatile compounds from the material. (The essential oils from aromatic materials).
- The second part is the condenser which cools and condenses the hot vapours, returning them to a liquid state.
- The third part is the receiver where the distillate collects and the essential oils are easily separated from the water.
Each part of the distillation train can be modified to perform extra functions, but this is the principal division of things.
The pot or boiler.
To make a simple pot still for steam or hydro distillation, one can use any clean metal kitchen pot with a tight-fitting lid.
A hole is drilled in the lid to accommodate a pipe that directs the hot vapors to the condenser.
A gasket of some sort is often required between lid and pot. Without a tight seal, any hot vapor that escapes the pot during distillation will carry your essential oils with it. Working at atmospheric pressure reduces the need for radical sealing methods and this can be accommodated by making sure the pipe leading from the pot to the condenser is wide enough to prevent buildup of pressure in the pot.
It is sometimes possible to seal the pot with Teflon plumbing or gas fitting tape, which is inert and will not leach adhesives into your still. If needed an adhesive tape of some sort can be wrapped tightly around the Teflon tape to hold it in place.
Pressure cookers can work as distillation pots and have the benefit of a fitted seal. Though contrary to the function they were designed for, pressure should not be allowed to build up pressure.
Since writing this post 3 years ago, I have shifted away from using Aluminum pots as the one shown here. Though in theory, molecules of Aluminum will not transfer to the receiver or essential oil, and they likely could be used safely for distillation or steam production, it is impossible to know for sure and my focus has shifted to the more traditional and customary copper, stainless steel and glass distillation systems. In this case, a stainless steel pressure cooker will serve just as well as an aluminum version.
An excellent and versatile distillation unit can be made of a stainless steel “Couscousiere”, a 2 tiered traditional Moroccan cooker as shown in a more recent post –How to make an essential oil still at home. A distillation workshop
- When modifying a pressure cooker for home distillation there are some important points to keep in mind.
- it is likely a good idea to leave the safety release valve on your pressure cooker intact. Otherwise, unlikely as it may seem, if your exit vent gets clogged, a pressure cooker can turn into a deadly bomb.
- If using the pressure cooker for simple hydro and steam distillation remove the pressure gauge or the jiggly thingy, and drill through its threaded seat for your steam exit.
- Make sure you have at least a 1/2 of an inch diameter passage for the hot vapors to exit the pot. Since writing this post I now personally avoid any fittings that are less then 3/4″. 1 inch is my ideal on this sized pot.
In the distillation shown here I used a 21.5 liter All American pressure cooker.
This system is different from the more familiar “press and turn” locking system that most home pressure cookers incorporate. It provides an elegant and enduring alternative to rubber and silicone gaskets through a milled aluminum top and seat. No gasket is needed and the 6 screw down clamps create an even pressure and a perfect seal. Tighten them as you would the wheel on a car, in pairs of opposing nuts. This helps make sure the lid is sitting evenly and properly in its seat.
I removed the pressure gauge, drilled a 1/2 inch hole and inserted a 1/2 inch brass fitting through the hole and screwed on a matching female fitting with Teflon tape on the inside of the lid. This diameter vent, (1/4″), is suitable for distilling liquids.
Herbs resins, barks and other materials are more safely distilled using a larger 1/2″ to 2″ exit hole to avoid clogging and building up pressure in the pot.
Adjustable couplings with elbows allow the pipe to swing horizontally and vertically to accommodate easy positioning of the condenser and receiver. All parts are available at most hardware stores.
In this example, I use an electric hot plate as a heat source which is not ideal. Electric elements don’t disperse the heat well and can burn the material in a thin bottomed pot, especially if there is a water-soluble component to the distilled material that will create a sludge. Even the smallest bit of burnt material in the pot can spoil the batch of essential oil. A thick bottomed pot is ideal, as is a gas heat source.
Though one can make a coiled copper tube condenser, or a metal water-cooled sleeve condenser at home, by far the easiest solution for the beginner is to purchase a ready made glass condenser. They are available from laboratory supply houses or eBay from about $20 to $60. I prefer to support small businesses and get mine from alchemylabsupply.com . A Leibig condenser is a simple glass “sleeve” condenser and an Alihn condenser has a series of glass “bubbles” to extend the cooling surface area. They range in length from 200 mm. To 600 mm. I find 300 mm to 400 mm. the most convenient.
The hot vapors pass from the pot, through the central glass tube, while cold water enters one end of the surrounding sleeve and exits the other, cooling down and condensing the vapors. I prefer these 2 condenser designs when distilling different materials since they are relatively easy to clean between distillations.
The water supply in this particular distillation is taken off a household tap and is collected and reused in the home/garden after passing through the condenser. All the adapters for the water hookup can be purchased at a hardware store.
One can use a large pot of water and an aquarium pump to circulate cooling water through the condenser as long as one keeps an eye on the temperature of the water in the reservoir. It will warm up and become less effective overtime as it runs though the hot condenser.
There is also the option of using an air-cooled condenser and I hope to go into detail around this option in another post.
Last but not least important is our receiver. Any narrow-necked, clean glass vessel will do.
There are siphon systems that attach to the receiver and help with separating the volatile oils from the water. In most cases the oils will float on top.
A simple method is to siphon or draw them off at the end of the distillation process and transfer them to a separatory funnel which allows easy removal of the heavier liquid from the distillate.
If you intend to collect the hydrosol, make sure your receiver is sterile otherwise it is easy to introduce organisms that will quickly spoil it.
Once the essential oils have been isolated they should be stored in a cool place.
That’s about it…….
Distilling different aromatic materials in a pot still
The distillation in the above pressure cooker pot still example was a hydro distillation of oleo-resins.
- As a general rule, I try to keep my water level between 1/2 and 2/3 the height of the pot.Any higher and there is a risk of liquid splashing or foaming over into the condenser, or plant material blocking the exit vent.
- Always measure exactly how much water you put in the pot. If possible use a graduated receiver that will easily show you exactly how much distillate has come over and thus, how much water is left in your pot..
- For plant material that needs to be steam distilled, a sieve or perforated container can be suspended above the water. With a little improvisation it can be supported by the lid, sides or bottom of the pot. For an example see Distilling Frankincense essential oil.
- The amount of essential oil you will extract from different materials varies greatly. Oleo-resins yield much more essential oil per kilogram material than flowers for example, and even between different oleo-resins there is great variation. Some Frankincense types yield 0.05% essential oil, while others yield 10% and more. Some fragrant seeds are quite high in essential oil content and others less so.
- Fresh, or gently dried aromatic material is preferred for both quantity and quality of essential oil yield.
As a general guideline, it could be said that different materials could be distilled thus-
- Oleo-resins with no water-soluble gum content can be distilled by hydro distillation directly in the water. These include Pine, Spruce and Fir saps, Mastic, Elemi, Copals and Frankincense Frereana.
- Oleo-resins with water soluble gum, or oleo-gum -resins such as most types of Frankincense and Myrrh, need extra attention when using a flat-bottomed pot still. They can be suspended in a sieve/colander above the water, or distilled very gently with a higher ratio of water to distilled material so less sludge and no burning occurs. The water soluble gums dissolve in the water and can create a slur that is apt to burn if the water level gets too low. When using flat bottomed pots, a thick bottom and a flame for a heat source, help reduce the risk of burning your material and losing the whole batch of essential oil.
- Aromatic seeds such as cumin, carrot, Dill etc can be distilled either suspended in a sieve or gently and directly in the water.
The beauty of water and steam distillation of this type is that you will never go above 100 degrees Celsius in the still, which is suitable for distilling most essential oils for apothecary, perfume and aromatherapy use.
If a hole is drilled in the pot lid, a thermometer can be inserted through a cork, and the temperature of the vapors can be finely controlled. This is important when distilling alcohol for instance.
I’m sure I have missed some important points. So feel free to leave any questions, ideas, insights or omissions in the comments section below. They are most welcome and appreciated.