Annealing

All fabrication induces stress in acrylic sheet. Annealing to relieve this stress is recommended to minimize crazing or cracking that can occur. Annealing can also increase bond strength by 50 percent.

Anneal parts in a forced air-circulating oven. Commercial ovens are designed for annealing and heating plastics; restaurant-type ovens also do the job. Heat the acrylic sheet to 180F, just below its deflection temperature and cool slowly. Heat for one hour per millimeter of thickness -- at least two hours total. Cooling time should be a minimum of two hours. For sheet thicknesses above 8mm, cooling time in hours should equal thickness in millimeters divided by four.