Alginate is a product used to make high-detail casts at room temperature. It is a naturally occuring substance rendered from seaweed. It's rendered form is a fine dry powder. When mixed with water, dependant on the formulation and water temperature, alginate gels and sets in 5-15 minutes. Alginate is especially popular in lifecasting. Alginate is also referred to as dental alginate or prosthetics alginate. There are slight variations in properties between the two products.