How to Use Polariscope for PET & Preforms to Check Residual Stress | Presto Demo Residual stress can lead to cracking, uneven wall thickness, and bottle failure. In this video, Presto Stantest, Asia’s No.1 testing equipment manufacturer, demonstrates how to use a Polariscope to inspect PET preforms and bottles for internal stress. Ensure dimensional stability and avoid defects before blow molding begins. Contact us at +91 9210 903 903 or info@prestogroup.com for premium quality testing instruments tailored to your needs. For more information visit our website: -https://www.prestogroup.com/categories/polariscope/