Soda ash is one of the alkali substances that are crucial in glassmaking and soapmaking. The famed clarity of 16th-century cristallo glass from Murano and Venice depended upon the purity of "Levantine soda ash", and the nature of this ingredient was kept secret. Spain had an enormous 18th-century industry that produced soda ash from the saltworts (barrilla in Spanish).
Soda ash plays a key role in glassmaking and soap production. The exceptional clarity of cristallo glass from Murano and Venice during the 16th century was due to the high-quality "Levantine soda ash" used, which was carefully guarded as a secret. In 18th-century Spain, a significant industry emerged that produced soda ash from saltworts.