Understanding Lightfastness in Colored Pencils

Every artist, whether a seasoned professional or an enthusiastic hobbyist, eventually faces a quiet but persistent enemy: the sun. You spend forty, sixty, or even a hundred hours meticulously layering wax or oil-based pigments to create a masterpiece. Yet, without an understanding of lightfastness, that vibrant portrait or lush landscape could become a pale shadow of its former self in just a few years.

In the world of fine art, permanence is the ultimate mark of quality. When we talk about lightfast colored pencils, we aren’t just discussing the richness of the laydown or the buttery texture of the lead. We are discussing the chemical stability of the pigments and their ability to withstand the relentless energy of ultraviolet (UV) radiation. This guide dives deep into the science, the industry standards, and the practical choices you must make to ensure your art outlasts you.

What is Lightfastness? The Science of Pigment Stability

Lightfastness refers to the inherent ability of a pigment to resist fading or changing hue when exposed to light. It is crucial to understand that lightfastness is a property of the pigment itself, not the binder (the wax or oil that holds the pigment together). While the binder affects how the pencil feels on paper, it offers very little protection against the photochemical reactions that cause fading.

When light hits a colored surface, the pigment molecules absorb certain wavelengths and reflect others, which is how we perceive color. However, high-energy UV rays can break the chemical bonds within those pigment molecules. When these bonds break, the molecule can no longer reflect light in the same way, leading to a loss of saturation or a complete shift in color. For more on the foundational concepts of this process, you can explore this comprehensive guide to lightfastness.

In the manufacturing world, creating lightfast colored pencils is a balancing act. Some pigments, like earth tones derived from iron oxides, are naturally stable and can last centuries. Others, particularly bright “fugitive” colors like fluorescent pinks or deep purples, are notoriously difficult to stabilize. Professional-grade manufacturers spend years sourcing specific synthetic organic or inorganic pigments that can survive the rigorous testing required for archival status.

The Industry Standards: Decoding ASTM and Blue Wool

As you shop for professional materials, you will notice various ratings on the barrels of your pencils. These aren’t just marketing fluff; they represent standardized testing results. The two most prominent systems are the American Society for Testing and Materials (ASTM) and the Blue Wool Scale. Understanding these is vital for any artist intending to sell their work or display it in a gallery.

The ASTM D6901 standard is the gold standard for colored pencils. It was developed in collaboration with the Colored Pencil Society of America (CPSA) to provide a reliable metric for artist-grade materials. Under this system, pencils are rated from I to V. Lightfast colored pencils rated as ASTM I (Excellent) or ASTM II (Very Good) are considered “archival” and suitable for professional use.

The Blue Wool Scale, originally developed for the textile industry, is also common, especially among European manufacturers like Faber-Castell or Caran d’Ache. This scale ranges from 1 to 8, where 8 represents the highest level of lightfastness. Most professional pencils aim for a rating of 6 or higher.

For those looking for a manufacturer’s perspective on how these standards are integrated into product development, Caran d’Ache’s guide for professional use offers excellent insight into how they engineer their Luminance line to meet these strict requirements.

The Danger Zone: Why Certain Colors Fade Faster

It is a frustrating reality for artists that not all colors are created equal. Even within a single high-end set of lightfast colored pencils, you might find that the ochres and umbers are indestructible while the bright violets are vulnerable. According to research from the Colored Pencil Society of America (CPSA), “hot” colors like pinks, purples, and certain oranges are chemically more prone to degradation.

This is because the pigments used for these vibrant hues often have more complex chemical structures that are more easily disrupted by photons. For example, many traditional carmine reds or magenta-based pigments are derived from organic compounds that lack the “sturdiness” of mineral-based pigments. When a manufacturer labels a pencil as “Lightfast,” they are often substituting these fugitive dyes with more expensive, stable alternatives that can mimic the hue without the risk of disappearing.

This is why “Neon” or “Fluorescent” pencils are never found in professional archival sets. The chemicals required to produce that glow are inherently unstable. If you are working on a commission, it is always safer to mix your purples from a stable blue and a stable red rather than relying on a single-pigment purple that lacks a high lightfastness rating.

The Value of Investing in Professional Grade

Why pay $4.00 for a single pencil when you can buy a pack of 50 for $10.00 at a local grocery store? The answer lies almost entirely in the pigment load and the lightfastness. Budget pencils use “hues” created with cheap dyes and a high percentage of fillers (like kaolin clay or wax). While they may look bright initially, they are not lightfast colored pencils and will begin to fade within months if kept in a room with a window.

Professional pencils, such as the Caran d’Ache Luminance, Derwent Lightfast, or Faber-Castell Polychromos, use high concentrations of pure pigment. Beyond the longevity, these pencils allow for better layering and blending because they aren’t “diluted” by excessive fillers. For the serious artist, this isn’t just about the art looking good today; it’s about protecting the financial and emotional investment of the collector. If a collector buys a piece for $500 and it fades within two years, the artist’s reputation is irreparably damaged.

Conducting Your Own Lightfastness Tests

While manufacturer ratings are generally reliable, many artists prefer to verify these claims themselves. Factors like the type of paper used (alkaline vs. acidic) and local climate (humidity and UV intensity) can affect how a pencil performs. You don’t need a laboratory to perform a basic test; you just need a sunny window and some patience.

To conduct a DIY test, create two identical color charts on the paper you use most frequently. Apply the lightfast colored pencils with heavy, medium, and light pressure to see how the pigment behaves at different saturations. Cut the chart in half. Place one half in a dark drawer and tape the other half to a south-facing window (in the northern hemisphere).

After three to six months, compare the two samples. If the window-exposed sample looks significantly lighter or has shifted in hue, that pencil is not archival. For a detailed walkthrough on setting up this experiment, Carrie L. Lewis provides an excellent artist-led tutorial on her blog.

Manufacturing Insights: How Lightfast Pencils Are Made

From a manufacturing standpoint, creating a lightfast range involves rigorous supply chain management. A pencil brand doesn’t just “make” pigment; they source it from chemical manufacturers. The challenge is that a pigment might be lightfast in an acrylic paint (where it is encased in a plastic polymer) but not in a colored pencil (where it is held in a porous wax/oil matrix).

The R&D process for lightfast colored pencils involves “accelerated aging” in a Xenon Arc machine. This device subjects the pencil marks to intense, concentrated light that simulates years of gallery exposure in a matter of weeks. If a batch of pigment fails this test, the manufacturer must go back to the drawing board to find a different chemical variant. This intensive testing is what drives up the cost of professional supplies, but it also provides the “peace of mind” that professional artists require.

Beyond the Pencil: Protecting Your Artwork

Even the most lightfast colored pencils cannot fight the sun alone indefinitely. To ensure your work lasts for generations, you must consider the entire “archival ecosystem.” This starts with the paper. Using 100% cotton, acid-free (pH neutral) paper is non-negotiable. Acidic wood-pulp paper will yellow and brittle over time, and that acidity can actually attack the pigments in your pencils.

Furthermore, the way you frame your work matters more than you might think. Standard glass offers very little protection against UV rays. Professional artists always recommend UV-protective “Museum Glass” or high-end acrylic like Optium. These materials can filter out up to 99% of harmful UV radiation, providing a second line of defense for your pigments.

Finally, consider the environment where the art is hung. Even with archival pencils and UV glass, a drawing should never be placed in direct sunlight. Indirect light or controlled LED gallery lighting is the safest way to showcase colored pencil art without risking the integrity of the work.

Final Thoughts: Making an Informed Choice

Choosing lightfast colored pencils is one of the most important decisions an artist can make. It represents a transition from “making drawings” to “creating fine art.” While the initial cost of archival sets can be daunting, the value they provide in terms of performance, blendability, and permanence is unmatched.

By understanding the ASTM and Blue Wool scales, recognizing the vulnerability of certain colors like pinks and purples, and implementing proper preservation techniques, you can ensure that your creative vision remains as vibrant fifty years from now as it is today. Art is an investment of your time and soul; don’t let the sun steal it away. Focus on quality, check the labels, and always prioritize the permanence of your pigments.

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