Hydrosols are the water (polar) portion of the result of steam distillation of botanicals. They are often called floral waters (such as Rose Water). They contain a relatively small amount of dissolved essential oil and are increasingly used in place of essential oils for a water-based milder version of botanical extract. In the above image, the blue German Chamomile essential oil is seen accumulating at the top and in bubbles adhered to the side of the collection vessel. The hydrosol is the cloudy solution below the essential oil.
Sometimes, water-based room sprays and essential oil spritzers are marketed as hydrosol. This is inaccurate as hydrosol is defined specifically as a direct product of steam or hydro distillation; not just a mixture of water and essential oil. Hydrosol will have a different chemistry than the aforementioned mixture since some compounds picked up during distillation will be present in a hydrosol while not in the essential oil.
Since hydrosols do also contain small amounts of dissolved essential oils, our practice is to recirculate the hydrosol back into our boiler (cohobation). It is then turned back into steam and passed through the plant material again… and again… and so on until the distillation is finished. We do this for a few reasons; first, in an attempt to reclaim the trace essential oils from the hydrosol, second, to allow longer distillation times (when needed) with the same amount of water, and third, because we do not have enough cold storage to keep large amounts of hydrosol fresh.
While hydrosol does come out of the still sanitized, just passing through a few inches of air can introduce a few bacteria and mold spores. With prolonged storage these contaminants can multiply and cause a “bloom” in the hydrosol. Refrigeration and trace dissolved essential oils can minimize this growth but not indefinitely. Preservatives can be used but are not often desired by natural product makers (Witch Hazel astringent is usually Hamamelis virginiana hydrosol with 14% ethanol content).
For this reason we do not sell hydrosols as a general rule of thumb. That said, if you are interested in larger volumes of hydrosols (1+ gallon), we may be able to accommodate you on a case by case/pre-order basis; especially if we already offer essential oil of the same species. If you would like to inquire about bulk hydrosols, please feel free to reach out to us!