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Drying Essential Oils.

  • Writer: Essential Stills
    Essential Stills
  • Nov 9, 2022
  • 2 min read

Updated: Apr 28, 2025

After draining the oil collected in the receiver, it’s time to remove any remaining water in the oil: your essential oil will now need 'drying'.

Take a glass pear-shaped separation flask containing the oil and place in the support ring on your laboratory stand.

Carefully tap off the visible water layer at the base: this is hydrosol and can be used in the production of various products including soaps etc. The oil is now visibly free from water but will still be saturated and in need of dehydrating. If this water is not removed the essential oil can possibly hydrolyse in time, i.e. it may react chemically with water it contains - and this process can create some undesirable off-notes.

Always keep a bung in the top of your separator except when letting liquid out at the bottom tap: the stopper should then be raised a little to let the air in. If you forget this move it will create a vacuum and 'bubble' - mixing everything back together again!

Now place a funnel with a wide stem in the top if the separation flask and add about two tea spoonsful of anhydrous sodium sulphate, a simple salt that is quite harmless. It is a white powder and will remove the last vestiges of water from your oil while itself becoming the hydrated sodium sulphate in the process.

Replace the stopper and gently shake and swirl the contents for a few seconds and then, with the stopper firmly in place, hold the separator upside down and open the tap. There will be a slight rush of air as the pressure equilibrates: then immediately shut the tap and turn the separator the right way up. Repeat this procedure a few times more until no further air escapes when the tap is opened. By now some of the sodium sulphate will have absorbed the water and taken on the ‘crystalline’ appearance of its hydrated form, whilst your oil should have become absolutely crystal clear. If the oil is still slightly murky, give the sodium sulphate a little longer to do its job, then repeat the swirling. If all else fails, add a little more of the dessicant - the anhydrous sodium sulphate, and that should do the trick.

You will then need to filter the dried oil to remove the salt crystals. Line a funnel with a filter

disc and carefully filter into a suitable glass receiver making sure to keep the oil within the filter paper. Don’t overfill the funnel so that the oil overflows and runs between the filter paper and the glass.

When finished, label the bottle with the name of the essential oil, date etc. and store in a cool place.


 
 
 

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More Information

 

 

What is it?

 

This Still comprises a boiling vessel with 6 elements at the base and a basket inside. A tall steam collection cone is fitted on top of the boiling vessel that carries a bend at its top that then joins onto an open horizontal 4” tube. This tube ends in a 90° bend that points downwards and this then joins on to the condenser with a 4” screw fitting.

 

​The condenser is a beautiful piece of kit with 36 narrow (8mm) thin-wall tubes fitted equidistantly within a 4” diameter stainless outer tube: there are 3 sets of baffles fixed at set intervals to make the water ‘chicane’ and maximise agitation and therefore improve its cooling capability. There is a cone at the base of the condenser to direct the distillate into the glass Florentine fitted directly underneath.​

 

How it Works:

 

The water boils, the dry steam goes through the plants in the basket collecting a bit of essential oil on the way and continues up the cone: at the top it turns 90°, goes through the top pipe and then heads down through the 36 pipes in the condenser. Since these pipes are surrounded by cold water, the steam then condenses into liquid and drops into the glass Florentine that is placed underneath. Here any oil present will separate and float to the surface, while the condensed water then trickles back to the boiling vessel via the S trap mounted a few inches up from its base.

 

​How to Operate:

 

Lift off cone/condenser unit and slide to one side and remove basket. Fill vessel with 40 - 50 litres of water, enough to cover the elements with say, an inch of water on top. Line basket with muslin and fill it with the material you want to distil e.g. lavender - and place it back inside the boiling vessel. Some form of lifting apparatus will be required e.g. simple sliding block and tackle. ​Slide cone/condenser unit back and lower onto boiling vessel, lock the clamps so that it all becomes one unit and turn on the heat. The Still has a wrap-around fabric insulation jacket made in two sections and one goes over the cone whilst the other goes around the boiling vessel. As the Still heats up, you can turn off some of the elements until a nice rolling boil is achieved. Make sure water is gently flowing through the condenser to keep it cold and the distillation continues until the oil layer in the Florentine stops growing. Then turn off heat and water and remove oil.

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