Drying Essential Oils.
After draining the oil collected into a cylinder it’s time to remove any remaining water in the oil.
Take a glass separator containing the oil and place in the support ring on your laboratory stand.
Carefully tap off the visible water layer at the base. The oil is now visibly free from water but will still
be saturated and in need of dehydrating. If this water is not removed it can possibly hydrolyse in
time, i.e. it may react chemically with water it contains. This process can create some undesirable
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 mix 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 salt 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 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 anhydrous 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 so that it overflows and runs between the filter paper and the glass funnel.
When finished label the bottle and store in a cool place.