What is the purpose of a hydrosol?
Short answer
Hydrosols replace some or all of the water in a formula and bring their own properties: soothing, toning, astringent or refreshing.
Explanation
In the skincare book, chamomile flower water (55.6%) is the soothing base of the foam cleanser. The toner combines witch hazel (a natural astringent for pores and oil), peppermint (refreshing, cooling) and rose hydrosol (soothing, softening acid irritation). Neroli hydrosol tones and balances in the anti-aging cream, and immortelle hydrosol forms the base of the firming gel.
In soap, damask rose hydrosol replaces part of the liquid in the Fresh-Cut Rose bar. It's added to the oils, because hot lye water would destroy its compounds.
What to do
- Treat hydrosols like water: they need a preservative in the finished product.
Source: The Big Book of Homemade Skin Care, The Big Book of Homemade Soap — Calming Chamomile Foam Cleanser · Clarifying Bio-Balance Toner · Fresh-Cut Rose Luxury Bar