Wheatpaste, or potato paste, (also known as flour paste or simply paste) is a liquid adhesive used since ancient times for various arts and crafts such as book binding, decoupage, collage, montage and papier-mâché. It is also made for the purpose of adhering paper posters to walls. Closely resembling wallpaper paste, it is made by mixing roughly equal portions of flour and water (some argue using more water or more flour), and heating it until it thickens.