Catharina Oostfries, or Trijntje Sieuwerts (1636–1708) was a Dutch Golden Age glass painter.
Biography Oostfries was born in Nieuwkoop. According to Houbraken she kept up her drawing and glass painting into her seventies. Catharina Oostfries Biography in De groote schouburgh der Nederlantsche konstschilders en schilderessen (1718) by Arnold Houbraken, courtesy of the Digital library for Dutch literature
According to the RKD she was the daughter of Siewert Oostvries, and was also known as Trijntje Siewerts.Catharina Oostfries in the RKD She was trained by her older brother Jozef Oostfries, a respected glass painter in Hoorn. She married the glass painter Claes Pietersz van der Meulen, and their son Sieuwert van der Meulen also became a painter. Her sister Heiltje married the painter Jan Slob, who had been a pupil of her brother. on genealogie onlineJan Slob Biography in De groote schouburgh She died in Alkmaar.
References
Catharina Oostfries on inghist