ASTM
Plural: ASTMs (rarely used; usually the acronym remains unchanged)
ASTM definition
ASTM is an organization that creates official standards used to test and classify materials, including artists’ paints. In painting, ASTM is most commonly seen in relation to lightfastness, meaning how well a pigment resists fading when exposed to light.
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ASTM (American Society for Testing and Materials) is an international organization that develops technical standards and testing methods to evaluate the quality, performance, safety, and durability of materials and products.
In the context of fine art materials, ASTM standards are used to classify properties such as pigment permanence, lightfastness, and durability of artists’ paints.
The most common ASTM classification encountered by artists is the ASTM D4303 standard for lightfastness of artists’ paints, which evaluates how resistant a pigment is to fading under controlled light exposure.
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ASTM I: Excellent lightfastness. The pigment is extremely stable and suitable for artworks intended to last for many decades or centuries.
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ASTM II: Very good lightfastness. The pigment is durable but slightly less permanent than ASTM I.
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ASTM III and lower: Lower levels of permanence, with a higher risk of noticeable fading over time.
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Examples
A tube of professional watercolor marked Lightfastness ASTM I indicates that the pigment has excellent resistance to fading. A pigment such as Quinacridone Magenta often receives an ASTM I rating because of its exceptional stability, while some traditional pigments may have lower ratings.
Context
For artists, ASTM classifications provide a reliable way to compare the permanence of different paints and pigments. They are especially important for professional painters, museums, collectors, and anyone creating artwork intended to survive for generations.
The ASTM rating does not describe the color quality, intensity, or mixing behavior of a pigment; it only measures specific performance characteristics, such as resistance to light-induced fading.
Core Principles
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Standardization: ASTM creates common testing methods so materials can be compared objectively.
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Permanence: In art materials, ASTM helps determine how long pigments can maintain their original appearance.
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Scientific evaluation: Ratings are based on controlled tests rather than subjective opinions.
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Material awareness: Understanding ASTM classifications helps artists choose pigments appropriate for archival artworks.
Derivation
The acronym ASTM originally stood for American Society for Testing and Materials, founded in 1898. The organization later adopted the name ASTM International to reflect its worldwide scope.