ASTM D7133

ASTM D7133 is the ASTM standard for measuring the tristimulus CIELAB color and yellowness index of liquid polyurethane raw materials. It provides a common reference for evaluating liquid color characteristics with instrumental methods, helping users compare materials more consistently. Because color can be an important indicator in raw material handling, quality control, and product consistency, this standard supports more reliable testing and more meaningful supplier-to-supplier or batch-to-batch comparisons.

What is ASTM D7133?

ASTM D7133, Standard Test Method for Polyurethane Raw Materials: Instrumental Measurement of Tristimulus CIELAB Color and Yellowness Index of Liquids, defines a test method for measuring the color properties of liquid polyurethane raw materials using instrumental color measurements. The standard focuses on tristimulus CIELAB color and yellowness index, which are commonly used to describe appearance in a more objective way than visual inspection. As a technical document, it helps standardize how these liquid materials are evaluated for color-related quality assessment.

Where is ASTM D7133 used?

This standard is commonly used in laboratories, incoming inspection programs, and quality control workflows that handle liquid polyurethane raw materials. It is relevant wherever instrumental color data is needed to compare material lots, monitor consistency, or document appearance-related characteristics during production or procurement. ASTM D7133 is especially useful in settings where liquid material color must be measured in a repeatable way and tracked as part of routine testing or supplier qualification.

Why is ASTM D7133 important?

ASTM D7133 matters because it gives manufacturers, labs, and buyers a clearer way to measure and communicate color-related properties of liquid polyurethane raw materials. Using a recognized standard can improve consistency, reduce ambiguity in color evaluation, and support more defensible quality control decisions. It also helps streamline compliance and procurement by providing a shared testing approach for instrumental color measurement, which can reduce risk when evaluating material performance and lot acceptance.

• Instrumental color measurement for liquids
• CIELAB and yellowness index evaluation
• Quality control and lot-to-lot comparison
• Testing for polyurethane raw materials