The process is a fairly straightforward one, though many seem pretty mystified by it. In many respects distillation hasn’t changed for centuries. It’s also not too different from the distillation of alcohol: relying on the same principles!
At the peak of our lavender harvest we usually do 4 distillations each day in our two stills. Our biggest still takes about 80kg fresh weight of lavender, and it takes about an hour distil the oil out. The lavender is packed into a steel mesh basket, weighed (at the end of the process we marry up the weight of oil with the weight of plant material to get an oil yield). The basket is winched into the stainless steel still. A lid is put on and bolted down. Steam is then introduced under pressure into the bottom of the still from our oil-fired boiler. The steam at 100°C rapidly rises through the lavender, heating it up.
All the different chemical components that make up the lavender oil (which is stored in tiny vesicles along the sides of each flower bud) have a boiling point less than the temperature of the steam. When heated by the steam the lavender oil boils, it expands, bursts out of the oil vesicles and in vapour form rises with the steam to the top of the still.
The steam and oil vapour pass through a short pipe into a water-cooled condenser. Here it is all cooled back to water and minute lavender oil droplets. This flows into a special glass flask – called a florentine flask – where the liquid settles and separates out into a water layer and a lavender oil layer. The lavender oil is lighter than water and being an oil does not mix with water so it floats on the top as a beautiful, golden coloured layer. From the flask the oil is drawn off and stored away carefully.
The excess water is returned to the bottom of the still, where eventually, after the distillation process it goes to waste. It smells like stewed grass, and is the colour of tea! We do sometimes keep the first 10 litres of water that is distilled off. This hydrosol, as it’s called, contains a very low level of lavender oil and can be used as ironing water, in cosmetics etc.
We also end up with a basket full of wet, soggy, discoloured, distilled lavender flowers. It is also sterile since it has has hot stem put through it. However we empty it all out onto a large heap, layer it up with other garden waste to put the bugs and bacteria back in, and turn it into compost for recycling on the farm.
To see this process taking place, come and visit Jersey Lavender. The harvest starts at the end of June – contact us to check exact dates – and lasts until the end of July. We do two detailed talks each day – 11.30am and 3pm. Don’t miss them. They are fascinating and the whole process is explained.
In a previous blog I described the harvesting process. In a further blog I’ll explain about the storing and maturing of lavender oil and oil yields.
This blog is largely taken from a page on our Jersey Lavender website titled About Lavender Oil.