Temperature control is a science. For hot washing PET, the goal is to maximize cleaning efficiency without damaging the polymer’s integrity. So, what is the “sweet spot”?

Through years of testing, it has been proven that 85°C to 95°C is the optimal range. At this temperature, the caustic soda and detergents in the hot washing tank work most effectively to break down glue bonds.

Why not cross 100°C? Many beginners think hotter is better. However, PET is sensitive to moisture at high temperatures—a process called hydrolysis. If the water exceeds 100°C, it can trigger rPET thermal degradation, causing a sharp drop in Intrinsic Viscosity (IV). A low-IV flake becomes brittle and loses its value for high-strength applications like spinning fiber or blowing new bottles. Our PET recycling line systems use precision sensors to maintain this delicate balance.