 The appearance of the word "glasswort" in English is reasonably contemporaneous with a 16th-century resurgence in English glassmaking, which had suffered a long decline after Roman times.This resurgence was led by glassmakers who emigrated to England from Lorraine and from Venice.The Lorraine glassmakers brought with them the technology of forest glass, the greenish glass that used potash from wood ashes as a flux.