A change in the apparent shape or position of an image viewed through or reflected by glass due to variations in flatness, curvature, thickness, refractive properties, assembly, or installation.
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Meaning and boundaries
Distortion is not the same as haze, color variation, low distinctness of image, or anisotropy, although several effects can be visible together.
Why it matters in glass restoration
Restoration that removes material unevenly can create local lens power or waviness, so optical evaluation is part of quality control.
Related terms
References
- National Glass Association — GANA Glazing Manual, 2022 edition
Publisher’s original source - National Glass Association — Methods of Measuring Optical Distortion in Heat-Treated Flat Architectural Glass
Publisher’s original source - ASTM International — ASTM C1652/C1652M-21(2025): Measuring Optical Distortion Using Digital Photography of Grids
Publisher’s original source - National Glass Association — Glossary of Terms for Color and Appearance
Publisher’s original source