Essential oils, except for a very few, should never be handled nor used neat and undiluted. They require a carrier such as a botanical oil or an emulsion-based formulation to be evenly dispersed in a cosmetic product. They can also be solubilized into aqueous bases in small amounts. Hair products carrying essential oils are likely to be light, sprayable oil (ester) formulations that can ensure the essential oils are safely and uniformly dispersed in the oil base. Certain essential oils used neat on hair may cause damage to the hair shafts. Research which essential oils are best for your hair type before including them in a hair care formulation. Lavender and rosemary are two popular beneficial essential oils for hair and scalp care.