Hydrosols are defined as "an aqueous solution or colloidal suspension of essential oils, usually obtained by steam distillation from aromatic plants". They are also called floral waters, hydrolates, herbal waters, or essential waters. They contain the water soluble molecules from the plant material, and generally have a pH of 5 to 6, which is perfect for skin care products!
The key to the hydrosols is the phrase "water soluble molecules", meaning anything oil soluble - like the phytosterols - are likely not found in the hydrosol. When you are buying a hydrosol, ensure it is an actual distillation not a combination of water and the essential oil of the plant (I've seen some that are water, emulsifier, and essential oil, so check the INCI or ingredient list carefully). They may be preserved or unpreserved - again, check this before buying the product. (The Herbarie notes their hydrosols are preserved with Cosmocil CQ, which may not work when introduced into an anionic environment - like a facial cleanser - so make sure you preserve these well! I couldn't find information on the hydrosols I get from Voyageur.)
How much hydrosol should you use? This is a very hard question to answer. Few suppliers have good information on their sites, but you can use most of them at 100% in a toner or linen water. (Always check with your supplier for suggested usage rates!) I like to use them at about 20% or so in my toners and liquid creations - this seems to be a nice level for getting the active ingredients and scents. You'll have to play with your hydrosols to see what you like.
Chamomile hydrosol - Like chamomile extract, it is known to offer great anti-inflammatory and anti-oxidizing properties. It offers good anti-irritancy qualities as well.
Clary sage hydrosol - Clary sage is good for oily skin and hair, and can benefit those with acne or dandruff. It can create a mucilaginous film that offers extra moisturizing and soothing.
Honeysuckle hydrosol - Like honeysuckle extract, it is a great anti-inflammatory ingredient, one of the best, with great free radical scavenging and chelating abilities. It offers good during and after sun exposure qualities and anti-bacterial, anti-fungal, and anti-viral properties. Good for acne prone skin, or those with reddened or irritated skin.
Lavender hydrosol - Lavender is good for soothing weather chapped or damaged skin. It offers cooling and soothing, and some anti-irritancy properties. Good for oily, dry, or mature skin - in short, everyone's skin!
Melissa hydrosol - Also known as lemon balm, it is anti-bacterial and anti-viral. It can be considered astringent, so dry skin types might not like it.
Orange flower or orange blossom (neroli) hydrosol - Filled with all kinds of astringent goodies, this is a great hydrosol for oily skin, not so great for dry skin. It can reduce redness and inflammation, and helps control sebum production.
Peppermint hydrosol - Peppermint offers a lovely cooling sensation and is great in summer or foot related products. It can increase circulation, act as a mild anti-septic and astringent, and can help with itching, although you want to keep it away from open wounds.
Rose hydrosol - Good for all skin types, it offers anti-bacterial properties and may help control sebum. It also smells really lovely.
Rosemary hydrosol - Like rosemary extract, the hydrosol offers all the wonderful water soluble polyphenols, and is good for oily skin. The ursolic acid creates a light film on your skin or hair, offering extra moisturizing. (Click on the rosemary extract links for more information!)
Join me tomorrow for fun formulating with hydrosols and extracts!