Glycerin is an expectant, a type of moisturizing agent that pulls water into the outer layer of your skin from deeper levels of your skin and the air. In skincare products, glycerin is commonly used with occlusive, another type of moisturizing agent, to trap the moisture that it draws into the skin. According to scientific research, glycerin is absolutely safe to use on the face. However, glycerin easily attracts and absorbs moisture, dust, and pollution, which can cause irritation to some people. Thus, you should ideally dilute raw glycerin in water or rose water before applying it to your face.