Lightfastness refers to a paint’s resistance to fading when exposed to various types of light, including sunlight and artificial light. It is a critical factor in determining how a painting will age over time.
An example of the Lightfastness Rating on acrylic and oil paint tubes is as follows:
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- Lightfastness I (or ***): Indicates excellent lightfastness. For instance, a tube of Phthalo Blue might have this rating, suggesting that it will remain vibrant and unchanged for many years, even when exposed to light.
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- Lightfastness III (or ): This rating signifies lower lightfastness. A paint with this rating, such as Alizarin Crimson, might fade or change color over time when exposed to light.
Lightfastness is a rating that is given to a paint according to ASTM (American Society for Testing and Materials) standard. The ASTM rating shows how good a pigment is at not fading when exposed to light. ASTM is short for the American Society for Testing and Materials. They make rules for how durable art supplies are, including how long a color keeps its brightness in light.In their rating system, I means the color stays bright the longest and V means it fades the quickest. But both I and II are good enough for artists to use.
To test how long a color stays bright, they mix the colors with Titanium White to make them reflect 40% of light (except for watercolor, where they use the paper’s whiteness). This test checks how much light bounces off the color. Then, they see how the colors hold up in sunlight and in a special fast-lighting test.
General Lightfastness Chart
This table (about lightfastness testing on wool, not acrylic paint in specific) shows how different lightfastness ratings compare on various scales. It gives an idea of how long colors with these ratings might stay bright under direct sunlight and in normal display conditions, like away from a window, in indirect sunlight, and behind UV protective glass.
For example: A pigment with an ASTM rating of I and a Blue Wool rating of 8, which signifies excellent lightfastness, can last over 100 years under normal display conditions, like being framed behind UV protective glass away from direct sunlight. Conversely, a pigment with an ASTM rating of V and a Blue Wool rating of 1, indicating very poor lightfastness, will last less than 2 years under the same conditions.
Source: Wikipedia
Which Lightfastness to Choose For My Artwork?
- For Artwork Meant to Last: If you’re creating art that you want to preserve for a long time, especially if it will be displayed in well-lit areas, choose paints with higher lightfastness ratings (I or II). These colors are more resistant to fading over time.
- For Practice or Temporary Work: If the work is for practice, short-term display, or you plan to digitize it, lower lightfastness (III or IV) can be acceptable, especially if these colors offer the hues or effects you desire.
- Considering Costs: Higher lightfastness often comes at a higher price, so balance your choices based on both the longevity needs of your artwork and your budget. (Don’t forget to read my 19 effective tips on how to save money as artist).
Here’s how lightfastness is typically measured and its effect on paintings:
Lightfastness Ratings and Light Types
- Exposure to Sunlight: Sunlight is the most challenging due to its ultraviolet (UV) rays. Paints with high lightfastness (rated I or II) can resist fading for decades under sunlight.
- Artificial Light: Fluorescent and incandescent lights also emit UV rays, but usually less intense than sunlight. High lightfastness paints are more resistant to these light sources as well.
- Years of Durability: A high lightfastness rating generally indicates that the color will remain stable and unchanged for 50 to 100 years or more under normal lighting conditions.
How Does Lightfastness Affect Paintings?
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- Fading and Color Change: Low lightfastness paints can fade significantly or change color when exposed to light over time. This can alter the appearance and intended expression of the artwork.
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- Preservation of Artwork: Paintings with high lightfastness ratings retain their original color integrity for much longer, ensuring the artist’s vision is preserved for future generations.
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- Artistic Choices: Artists may choose certain paints with lower lightfastness intentionally for specific effects, accepting that the work may be transient or protected from light exposure.
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- Conservation Efforts: Artworks with lower lightfastness ratings may require more conservation efforts, such as UV-protective glass or limited exposure to light, to maintain their appearance.
Understanding and considering the lightfastness of paints is crucial for artists who want their work to withstand the test of time, especially when exposed to light. This knowledge informs the selection of materials and the preservation strategies for artwork.
How To Test Your Paints For Their Lightfastness?
Here’s a good instruction on how to do your own lightfastness test. You don’t need to be put off by the technical jargon or equipment that professionals use.
To test your paints, treat it like a small art project. You can get all the supplies from an art store or by mail. Use the sun as your light source and your own eyes to judge the changes in the paint. Simply take a frame and paper, paint swatches of color, cover half of each with tape, and then expose it to sunlight. Over a few months, you can see if any of the colors fade. This hands-on test can give you real confidence in the paint you’re using, more than any published ratings.
Here is this webpage that offers detailed instruction about how to do your own lightfastness test.
Why Is It Super Important to Know Your Paints' Lightfastness Level?
Artists need to know about their paints’ lightfastness for several important reasons:
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Artwork Longevity: Understanding lightfastness helps artists ensure that their works can stand the test of time without significant fading or color change.
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Professional Reputation: Artists who sell or exhibit their work have a professional stake in the durability of their art. Knowledge of lightfastness can maintain their reputation for quality.
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Informed Material Selection: Knowing the lightfastness of paints allows artists to make informed decisions about the materials they choose for different projects, especially when creating art for bright or sunlit spaces.
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Preservation of Original Art: For collectors and museums, the lightfastness of paints is critical for the preservation of the artwork in its original form.
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Economic Efficiency: Artists can avoid wasting money on materials that may not last, selecting instead those that offer the durability required for their work’s intended purpose.
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Artistic Integrity: Lightfastness knowledge ensures that the original vision and experience of the artwork remain as true as possible to the artist’s intent over time.
Which Are The Best Acrylic And Oil Paint Brands with High Lightfastness Level?
Golden Acrylic Paint is widely recognized as a top acrylic choice for its vivid colors, robust texture, and wide color range. It’s known for top-notch lightfastness, scoring an ASTM I rating – the best for lasting color.
Liquitex Heavy Body Acrylics are also favored for their premium quality and excellent lightfastness.
For oil paints, Holbein stands out with a four-star lightfastness rating, ensuring paintings retain their color over time. These brands are chosen by artists for both performance and durability.
