Michelle Thompson | Your Hair & Skin bestie | Health Coach on Instagram: "Keratin treatments are often associated with formaldehyde. While they do not actually contain formaldehyde (because formaldehyde is a gas), many contain ingredients that release formaldehyde when they are heated or mixed with water. Examples include methylene glycol, methanediol, methanal and formalin. These chemicals are extremely effective sealers — they are the ingredients that keep your hair smooth and frizz-free. Howe