Green soap is synonymous with tattooing, so much so that it is known as "tattooist's soap" in many places. It is traditionally a soft soap that is predominantly made from vegetable oils. It also contains sodium or potassium hydroxide which helps to retain the glycerol. This soap is medically and environmentally safe. It is all natural and generally hypoallergenic and will not irritate the skin, meaning that it is suitable for use on all clients. It is also biodegradable, another reason it is known as "green soap" aside from the usual yellowish green tinge that naturally occurs. Due to the oil content, the soap acts as a natural emollient and cleanser meaning it is ideal for use after tattooing when the skin has been irritated from the needles and ink insertion. Although there are many alternative uses for green soap, it is mostly used in tattoo and piercing studios. It has a wide variety of applications including prepping the skin before a tattoo and soothing it once the tattoo has been completed. It is excellent at removing debris, blood and ink both from the skin and surgical instruments or equipment. It is often used as a pre-sterilisation soak for tattooing equipment and accessories, although the autoclave or ultrasound process should still be carried out afterwards.