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D5398-97 – Standard Test Method Technical Guide
ASTM D5398-97 (Reapproved 2010) provides a standardized practice for users to visually evaluate the lightfastness of colored art materials through indoor sunlight exposure. This method is designed for personal assessment and identification of materials requiring special light protection.
📋 Overview and Scope
This practice covers the exposure of art material specimens indoors to sunlight through a closed window, with color change compared to a Blue Wool Reference 3 (ISO Blue Wool Reference 3) exposed simultaneously. It is intended for users to select materials with satisfactory lightfastness for personal use or to identify materials needing protection from light. However, when communicating test information to others, Test Methods D4303 or Practice D5383 must be used.
This practice is suitable for indicating materials that will change color within months or years, but it is not rigorous enough to verify lightfastness for more than fifty years. The method is kept simple and requires no instrumentation. It is not suitable for evaluating high oil content materials like artists’ oil, resin-oil, or alkyd paints.
The values stated in SI units are standard. The standard does not address safety concerns, and users should establish appropriate safety practices.
⚙️ Test Procedure and Controls
The practice employs Blue Wool Reference 3 from a series of eight Blue Wool References of known lightfastness, developed for use with ISO/R 105-B and BSI 1006 Group B. Specimens are exposed to sunlight behind glass, and any color change is compared to the fading of the Blue Wool Reference.
The procedure is designed to be simple and short, allowing for execution without instrumentation. It is important to use a white, pH neutral substrate for applying the art materials.
⚠️ Important Note: This practice is not suitable for testing materials with high oil content, such as artists’ oil, resin-oil, or alkyd paints. Use specified standards like D4303 for rigorous evaluation.
📊 Key Terminology and References
The following terms are defined in this standard and are essential for understanding the practice:
| 🟦 Term | 📏 Definition |
|---|---|
| Bloom | A cloudy coating on colored pencil drawings due to wax migration, which can be made transparent by gentle polishing. |
| Fugitive color | A colorant that changes color in a few days or weeks, or bleaches white in less than 18 months, when exposed behind glass to sunlight. |
| Glazing | The transparent glass or plastic sheet placed in front of a picture when framed. |
| Substrate | The white, pH neutral paper or board on which art materials are applied. |
Referenced documents include ASTM D4303, D5383, E284, and ISO/R 105-B, BSI 1006 Group B.
❓ Frequently Asked Questions
🔍 What is the main purpose of ASTM D5398-97?
This standard practice allows users to visually evaluate the lightfastness of colored art materials by exposing them to sunlight through a closed window, using Blue Wool Reference 3 as a control. It helps identify materials that are fugitive or require special light protection.
💡 How is the test performed?
Specimens of art materials are applied to a white, pH neutral substrate and exposed indoors to sunlight behind a closed window. The color change is compared simultaneously with a Blue Wool Reference 3 exposure to determine lightfastness.
⚡ What materials are excluded from this practice?
Materials with high oil content, such as artists’ oil, resin-oil, or alkyd paints, are not suitable for this practice. For these materials, other standards like D4303 should be used.
📌 Why is Blue Wool Reference 3 used as a control?
Blue Wool Reference 3 is part of a series of eight references with known lightfastness, developed for ISO/R 105-B and BSI 1006 Group B. It provides a reliable benchmark for comparing color change under the specified exposure conditions.