Problem CategoryMaterials & Sheet Quality
Technical Guide

Acrylic Crazing After Thermoforming

Prevent fine cracks in thermoformed acrylic by controlling forming stress, moisture, machining, flame polishing, assembly load, and chemical exposure.

Crazing in acrylic appears as networks of fine cracks that scatter light. It can develop during forming, trimming, polishing, bonding, cleaning, assembly, or later service.

Both cast and extruded acrylic can be thermoformed, but they have different forming behavior and supplier windows. Residual stress from unsuitable forming temperature, sharp geometry, uneven cooling, or aggressive fabrication makes either type more sensitive to chemical attack.

Corrective action

The exact sheet product must be identified before a forming recipe is selected. Drying or conditioning should follow supplier guidance where moisture exposure is relevant. Machining tools must cut cleanly without overheating, and flame polishing should be used only with a process qualified for the stress state and edge geometry.

Solvent cleaners and adhesives require product-specific compatibility testing. A clear surface immediately after treatment does not rule out delayed crazing.