What Is Distillation Oil?

If you’ve ever watched a plant go through the distillation process, you may notice something beautiful happen after the distillation is complete: the oils begin to separate from the hydrosol.

This is exactly what happened with the batch I made last night.

You can use the hydrosol as it is, with the tiny amount of essential oil still dispersed throughout it, or you can separate and collect the essential oil as well.

For now, I’m keeping mine together.

So, What Exactly Is an Essential Oil?

Merriam-Webster defines an essential oil as: “any of a class of volatile oils that give plants their characteristic odors.” The word volatile is important here. In this context, it means that the aromatic compounds readily evaporate at normal temperatures.

When we distill aromatic plant material, heat and water are used to release these volatile aromatic compounds from the plant. The vapor travels through the distillation apparatus, where it cools and condenses back into liquid.

The resulting liquid is primarily the Hydrosol, while the concentrated aromatic oil may separate and collect on the surface.

The essential oil is therefore not simply the entire plant reduced down into an oil. It is a concentrated collection of certain volatile aromatic compounds naturally present in the plant.

And not every plant will produce a visible layer of essential oil. Some plants contain very little volatile oil, while others produce more.

What Is a Hydrosol?

A hydrosol is the aromatic water produced during the distillation process. You may also hear it called floral water or herbal water.

As the plant material is distilled, the steam carries volatile aromatic compounds with it. Once that vapor cools and condenses, you are left with an aromatic water containing water-soluble plant constituents as well as small amounts of volatile aromatic compounds.

Some of the essential oil may remain dispersed throughout the hydrosol, while the larger oil droplets eventually separate and rise to the surface.

That’s what you’re seeing here.

Watching the Separation

This is one of my favorite parts of distillation because you can actually see the plant separating into different preparations.

The hydrosol and essential oil came from the same plant material and the same distillation process, but they are not the same preparation. One is an aromatic water and the other is a concentrated aromatic oil.

This is where learning herbalism becomes so interesting to me. We aren’t just learning what a plant can do; we’re learning how different preparations change what we are able to work with.

Sometimes the lesson is right there on the surface.

Literally.

For now, I’ll be keeping the essential oil and hydrosol together and allowing the distillation to continue teaching me what this particular plant has to offer.

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You can see the oils have separated from the hydrosol. A hydrosol is also called floral water or herbal water.