Polysorbate 20 (also known as Tween 20) is a nonionic surfactant and emulsifier derived from sorbitol which comes from fruit and berries. Polysorbate 20 is a water-soluble liquid used as a dispersing agent and is a gentle, non-irritating, non-toxic solubilizer. A solubilizer is essential to blend fragrance and essential oils with various bases (shampoo, shower gel, creams etc). You may also add it to water, along with vodka, to make linen and body sprays.
Combine equal amounts of Polysorbate 20 and essential and/or fragrance oils. Shake well, and add while stirring gently to your base.