Silk amino acids, also known as silk protein or sericin, are the gelatinous proteins that bind the filaments in silk. The protein is water-soluble and is found in both liquid and powder form. These amino acids are used in a variety of cosmetic and personal-care products, including hair conditioner, hairspray, and skin creams.
The acids are obtained from a silkworm cocoon by either boiling the cocoon or piercing the cocoon with a needle. During the boiling process, the silk that makes up the cocoon unspools, thereby allowing the silk threads and the silk amino acid to be harvested. Regardless of the method used, the silkworm is killed in the process, which is the reason some animal rights groups condemn the process.
Silk protein is often used in hair care products because of its ability to penetrate and strengthen damaged hair. The amino acids bind with the keratin in the hair, thereby creating a protective layer that helps seal in moisture while adding luster. Several commercial hairsprays use these amino acids to provide extra protection and shine without weighing down the hair.
The amino acids have a low molecular weight that allows them to be easily absorbed through the skin. As with hair, silk protein binds with the keratin found in skin and creates a layer of defense against moisture loss. In addition, some studies have shown that the crystalline structure of sericin offers some protection from ultra-violet (UV) rays. Silk amino acids have some antioxidant properties and have been shown to be effective in combating wrinkles.
Other than its common use in ready-made cosmetics and beauty aids, consumer forms of liquid and powder silk amino acids are available to those interested in making their own personal-care products. A community of avid do-it-yourself home beauty product makers — with websites, blogs, and chat rooms devoted to recipes and methods — has embraced the substance’s versatility, moisture retention, and softening abilities. For example, a few drops of liquid silk amino acids can be added to commercially made mascara as a conditioning treatment for eyelashes.
While either liquid or power forms of sericin works well, hobbyists report liquid amino acids are usually easier to use in the making of lotions or creams. Powered silk amino acids can clump when added to ready-made compounds — a problem that can be neatly avoided with the use of a liquid form. There are few substances in nature that can offer the gentle moisture protection, anti-oxidant properties, and soft shine of silk protein.