The Riihimaki glassworks was founded in 1910, in the town of Riihimaki, Finland, by M. A. Kolehmainen and his son A. P. Kolehmainen. At first they made domestic glass and container glass, and began making glass bottles and window glass in 1919. Riihimaki became the largest glass factory in Finland after buying the Kaukalahti glassworks in 1927. Riihimaki was renamed Riihimaen Lasi Oy in 1937, and Aimo Okkolin began designing for Riihimaki in the same year. Helena Tynell joined Riihimaki in 1949, followed by Nanny Still in 1949, and Tamara Aladin in 1959. Together these four were chief designers for Riihimaki over the next 20 years, and produced a great many popular designs which can still be easily found today. In 1968 Erkkitapio Siiroinen began designing for Riihimaki as a freelancer. Riihimaki was bought by Ahlstrom in 1985, and merged with Karhula in 1988 under the name Ahlstrom Riihimaen Lasi Oy. in 1990 the Riihimaki factory was closed.
Sources: 20th Century Factory Glass by Lesley Jackson.