Thea B. van Oosten began her career in 1975 as a conservation scientist at the Cultural Heritage Agency of the Netherlands (RCE) and its predecessors. In 1989, she launched the agency’s research program on plastics. Specializing in the conservation of modern and contemporary art and design objects, she has contributed to numerous workshops, publications, and books, including Modern Art: Who Cares?, PUR Facts, Conservation of Polyurethane Foam in Art and Design, and The Preservation of Plastic Artefacts (POPART), and Physical Properties of Plastics: A Guide for Conservators. Since retiring from the RCE in 2011, she has worked as a freelance conservation scientist and adviser on plastics for various international projects focused on modern and contemporary art and design.Additionally, she is an associate researcher at the University of Amsterdam and a Fellow of the International Institute for Conservation of Historic and Artistic Works (IIC).