Colour consistency is critical across plastics, particularly in industries where appearance, branding, and product quality must be tightly controlled. Even small variations can lead to rejected batches, customer complaints, or visible inconsistencies in final products.

Visual assessment alone is not reliable. Lighting conditions, human perception, and material differences can all affect how colour is judged.

ASTM D6290 colour measurement testing provides an objective, standardised way to quantify colour in plastic materials, helping you ensure consistency, reduce waste, and meet specification requirements.

What Colour Measurement Testing Involves

ASTM D6290 is a standard method for the instrumental measurement of colour in plastic pellets, particularly focusing on degree of yellowness and overall colour characteristics.

The test uses a spectrophotometer or colorimeter to generate precise colour values, including:

• Yellowness Index (YI)
• CIE X, Y, Z tristimulus values
• CIE L, a, b* colour space values**
• Hunter L, a, b values

These measurements allow for accurate comparison between materials and batches, ensuring consistent colour performance.

Methodology

At Impact Solutions, colour measurement testing is performed using calibrated instrumentation in line with ASTM D6290 requirements.

A typical testing programme includes:

1. Preparation of representative plastic pellet samples.
2. Measurement using a spectrophotometer or colorimeter under controlled lighting conditions.
3. Capture of tristimulus values based on standardised colour systems.
4. Calculation of colour metrics, such as yellowness index and Lab* values.
5. Comparison against reference samples or specifications.
6. Detailed reporting with clear numerical data and interpretation.

The method allows for rapid and repeatable comparison of materials without the need for moulding or further processing.

Relevant Industry Applications

Colour measurement testing is widely used for:

• Plastic resin and pellet production
• Packaging materials
• Consumer goods and appliances
• Automotive interior components
• Medical and healthcare plastics
• Masterbatch and additive development

Benefits of ASTM D6290 Testing

• Provides objective, quantitative colour data
• Eliminates subjectivity from visual assessment
• Supports batch-to-batch consistency
• Enables comparison of raw materials and suppliers
• Helps detect colour shifts early in production
• Reduces risk of rejected products and rework

Need precise and reliable colour data for your materials?

Contact Impact Solutions to discuss ASTM D6290 colour measurement testing and ensure consistent quality across your products.

FAQ

Q: Why is instrumental colour measurement important?
It removes subjectivity and provides precise, repeatable data that cannot be achieved through visual inspection alone.

Q: Can this test predict final product colour?
It is useful for comparing pellet colour, but final product colour may vary depending on processing conditions.

Q: What is the Yellowness Index?
It is a measurement used to quantify the degree of yellowing in a material, particularly important for clear or light-coloured plastics.

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