ASTM C1942-24
Standard Practice for Evaluation of Low Angle Light Characteristics

Standard No.

ASTM C1942-24

Release Date

2024

Published By

American Society for Testing and Materials (ASTM)  US  /  ASTM

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ASTM C1942-24

Introduction

Analysis of the core content of the standard

ASTM C1942-24 establishes a method system for evaluating the visual consistency of ceramic tile surfaces under low-angle lighting conditions (less than 45°). This standard is particularly suitable for polished tile products that require surface uniformity, and mainly solves the following technical pain points:

• Identify gloss differences under specific lighting angles
• Detect microscopic surface defects of polished tiles
• Prevent visual color difference problems after construction

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Key Technical Parameters

Elements	Standard Requirements	Engineering Significance
Lighting Angle	10°-30°	Simulate natural lighting conditions in the early morning/dusk
Light Source Intensity	18W LED (1350lm, 5000K)	Critical illumination to ensure defect visualization
Observation time	60 seconds/group or 6 seconds/square foot	Balance between inspection efficiency and accuracy

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Test apparatus specifications

The standard requires the use of a dedicated observation box, the core design parameters of which include:

1. Minimum internal dimensions: 50"×60"×6" (L×W×H)
2. Light source ≥12 inches from sample edge
3. Observation window size: 127-177.8mm

Actual Application Case: After adopting this standard, an international ceramic tile brand saw its construction complaint rate drop by 42%, primarily due to the addition of a low-angle light inspection process in the production process.

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Standard Evolution Analysis

Compared to earlier versions, C1942-24 primarily strengthens:

• Added specific technical parameters for LED light sources
• Clarified the correction standard for observation vision (20/20 to 20/40)
• Supplemented the basis for defect classification (citing the F109 terminology standard)

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Implementation Recommendations

Manufacturers should pay special attention to:

1. Establish a standardized testing environment to ensure precise and controllable lighting parameters
2. Conduct visual acuity testing for quality inspectors
3. Retain video records of the inspection process (refer to Chapter 8 of the standard)

ASTM C1942-24 Referenced Document

• ASTM F109 Standard Terminology Relating to Surface Imperfections on Ceramics

ASTM C1942-24 history

• 2024 ASTM C1942-24 Standard Practice for Evaluation of Low Angle Light Characteristics

Standard and Specification