Glass Inspection
ASTM Glass Inspection Guidelines
Please follow these instructions when inspecting your glass upon delivery. This process ensures evaluation is consistent with industry standards and allows any concerns to be identified promptly.
● This inspection process is based on ASTM C1036 – Standard Specification for Flat Glass, the accepted industry standard for visual quality of transparent flat glass.
● X-Ray Lead Glass is a specialty, performance-based product; Quality Level Q3 under ASTM C1036.
How to Inspect the Glass
● Stand approximately 10 feet (3 meters) away from the glass.
● View the glass straight on (90° angle) to the surface.
● Inspect under natural daylight or uniform diffused lighting.
❗ Do not inspect in direct sunlight, as this can exaggerate normal characteristics.
● Inspection should be performed with the naked eye (or corrected 20/20 vision).
● The main viewing area of the glass does not include the outer 2 inches around the edges when checking for blemishes or imperfections.
Color and Appearance
X-ray lead glass will exhibit a natural yellow hue due to lead content.
This is normal and not a defect.
Understanding the Glass Zones
Divide the glass into three areas for inspection:
- Edge Zone – The 2-inch wide band around the outer edge.
- Main Zone – The large center area, which makes up about 80% of the glass.
- Rim Zone – The area between the Main Zone and Edge Zone (what’s left after removing the center and edges).
Blemishes (ASTM-Based Evaluation)
Glass is evaluated based on visibility at the prescribed viewing distance, not just size.
General Acceptance (Q3):
● Minor point blemishes (such as pinholes, inclusions, or seeds) are permitted if not visually prominent at 10 ft
● Linear blemishes (light scratches, rubs) are permitted if not immediately noticeable under standard viewing conditions
● Blemishes must not be:
- Clustered in a visually distracting manner
- Obvious under normal inspection conditions
Scratches
- Faint to light scratches are acceptable if not readily visible from 10 ft
- Heavy or highly visible scratches are not acceptable in the main viewing area
- Minor edge abrasions are acceptable
Distortion (Important for Lead Glass)
● All glass may exhibit minor optical distortion.
● X-ray lead glass inherently contains greater visual distortion due to:
- High Lead Content
- Manufacturing Process
- Thickness
● Subtle waviness, “water-like” appearance, or minor image distortion is normal and not considered a defect, provided:
- It does not obstruct general visibility
- It is not excessive under standard viewing conditions
Important Notes
ASTM C1036 establishes guidelines for conventional flat glass and does not fully account for the unique optical characteristics of leaded radiation shielding glass.
Acceptance criteria for specialty glass may require practical judgment based on intended function rather than optical perfection.
Questions or Concerns
If you have any questions about your order or the inspection process, please contact Lead Glass Pro right away. We’re here to help.