Hydrosols are produced during the steam distillation of plants and contain fat and water-soluble components from the essential oils of the processed plant. They also contain other water-soluble substances that are more volatile than water. However, since not only oil plants are distilled, Hydrolat essential oils must be present for extraction. Basically, hydrosols are very similar to the essential oil from which they were extracted. They can be used pure or as an ingredient in cosmetic products. They are even suitable as conditioners for the hair or as a bath additive.
see: Heike Käfer 2010 "Natural Cosmetic Raw Materials", Linz, Freya Verlag, 3rd Edition 2012