Spectacle Lens Manufacturing in the Low Countries

Timeline

1. 1570–1576Antwerp · BrabantAntwerp workshops blew colorless glass discs in the Murano style, then hand-ground them into convex and concave lenses; frames were made of copper, silver, or horn, sold classified as myopic (concave) and presbyopic (convex). Guild-style division of labor let blowers, grinders, and fitters each specialize.
2. 1576–1578Middelburg · ZeelandAfter Spain retook Antwerp, optical craftsmen migrated north into rebel-held territory: Delft and Middelburg (Zeeland) took up lens grinding and export. Zeeland ports could still ship spectacles to England, Germany, and the Baltic, maintaining continuity of the Low Countries' optical industry in the later 1570s.
3. 1578–1580Delft · HollandMerchants in Delft and Amsterdam packaged lenses and frames for export; workshops used the trial lens method to roughly estimate diopters—though without systematic refractive theory, lenses could already be customized by use. Low Country lenses of the late 1570s were renowned for transparency and grinding precision, providing material and skill reserves for the invention of the telescope in the 1590s.