An article includes a substrate and an intumescent coating to form an intumescent product in response to heating the article. The intumescent coating is disposed on the substrate and includes a primary intumescent precursor and a layered material that includes a silicate mineral, a layered double hydroxide, or a combination thereof. The primary intumescent precursor includes a carbohydrate polymer. A process for forming an article includes forming a liquid composition by disposing in a solvent a primary intumescent precursor and a layered material, contacting a substrate with the liquid composition, and forming an intumescent coating on the substrate to form the article.