Ingrain (or wood-chip) wallpaper is a decorating material. It consists of two layers of paper with wood fibre in between; different kinds of ingrain wallpaper are distinguished by the size and form of the fibre pieces. Ingrain wallpaper was invented by German pharmacist Hugo Erfurt in 1864; marketed by the company his grandfather founded, it was first used as a decoration for shop windows, but began seeing use as a wallpaper from the 1920s on as well. Ingrain wallpaper is the most commonly used type of wallpaper in Germany. It was also commonplace in the United Kingdom in the 1960s and 1970s.