By 1622, he had become one of the directors of the Amsterdam chamber of the recently founded Dutch West India Company. For years Blommaert was involved in the copper trade and industry. In 1627 he had an argument about a cargo of 34 Swedish guns. In 1628 he collaborated with Kiliaen van Rensselaer, Samuel Godijn en Albert Coenraetsz. Burgh. In company with Godyn, a fellow-director, he bargained with the natives for a tract of land reaching from Cape Henlopen to the mouth of the Delaware River. This was in 1629, three years before the charter of Maryland, and is the oldest deed for land in the state of Delaware. The purchase was ratified in 1630 by Peter Minuit and his council at Fort Amsterdam.