Menu

What Is Lightfastness And Why Does It Matter?

By Carol Leather

In short

Lightfastness measures how well a pigment resists fading when exposed to light, especially UV. On coloured pencils it is shown as a Blue Wool rating (1 to 8), a star rating (1 to 3), or an ASTM grade (LF1 to LF5). For work you want to last, choose pencils rated Blue Wool 6 or above, or LF1 to LF2.

Have you ever noticed your coloured pencil artwork fading over time? Understanding lightfastness can preserve your creations and save hours of effort from fading into obscurity under bright sunlight.

Lightfastness measures how well pigments resist fading when exposed to light, particularly harmful ultraviolet (UV) rays. For artists, this knowledge is key to ensuring their work retains its vibrancy and beauty for years.

Before examining lightfastness in colored pencils, here's how light affects different art materials:

  • Watercolours: With their delicate, thin layers, watercolours are especially vulnerable to fading. Completed pieces are often stored away from bright light or displayed cautiously under UV-protective glass to preserve their colours.
  • Oil Paintings: The thick layers and protective oil binders provide some resilience. However, many "Old Masters" paintings have lost their original vibrancy over centuries due to dirt, varnish degradation, and light exposure.
  • Acrylics: Modern acrylic paints benefit from durable polymer binders and advanced pigments, making them more resistant to fading than many traditional media.
  • Inks: Often derived from stable pigments, inks tend to be among the most lightfast water-based mediums.

Understanding these differences provides a valuable foundation for grasping how coloured pencils perform under similar conditions.

Lightfastness in Coloured Pencils

Coloured pencil art is as sensitive to light as other media and requires similar protective measures.

Certain pigments are more prone to fading: reds, purples, pinks, and some blues are often less stable than natural browns, yellows, and greens.

Thankfully, advancements in modern chemistry and synthetic pigments have led to fade-resistant formulations, especially in professional-grade coloured pencils.

The same drawing at completion and again after six months of Mediterranean sunlight. The fading is caused by non-lightfast pencils.

Why Older Pencils May Fade More Quickly

Older pencils often contain less stable pigments. Modern manufacturers, aware of the demand for durable colours, have improved their formulas. However, not all pencils are created equal.

  • Student and Budget Lines often use cheaper pigments that fade faster.
  • Professional Artist Lines feature higher-quality pigments with better lightfastness ratings but come at a premium price.

Why Do Watercolour And Wax Pencils Carry Different Ratings?

Lightfastness ratings differ between watercolour (aquarelle) and wax-based (non-soluble) pencils, even when the same pigments are used. This variation is due to the thickness of the pigment layer.

Wax-Based Pencils: Produce thicker, more resilient pigment layers resulting in higher lightfastness.

Watercolour Pencils: Create thinner layers when diluted with water, making them more prone to fading.

Caran d'Ache's Museum Aquarelles, launched in 2013, demonstrate that excellent lightfastness is achievable in watercolour pencils. Most score 3+ stars on the Blue Wool Scale, whether used wet or dry.

Caran d'Ache Museum Aquarelle watercolour pencils showing sun-symbol lightfastness star ratings on the barrel

Caran d'Ache Museum Aquarelles are watercolour pencils built for lightfastness. Each barrel shows a sun symbol and a star rating up to five. Terracotta here scores the full five stars and Burnt Sienna four, with three stars on the deeper colours.

How Is Lightfastness Measured?

The point

Three systems dominate: the Blue Wool Scale (1 to 8), star ratings (1 to 3), and ASTM grades (LF1 to LF5). Aim for Blue Wool 6+, three stars, or LF1 to LF2 for artwork you want to keep.

Lightfastness ratings measure a pencil's resistance to fading. Common rating systems include:

Blue Wool Scale: 1-8, with 8 being most lightfast. Ratings of 6+ are suitable for professional work.

Star Ratings: 1-3 stars, where 3 stars indicates high durability.

ASTM Ratings:

  • ASTM D6901: Tests lightfastness on coloured pencils directly, providing highly reliable results. LF1 (excellent) and LF2 (very good) are the highest ratings.
  • ASTM D4303: Evaluates the pigments used in pencils and other art materials. While less specific to the pencil itself, it offers a good indication of colour longevity.

Avoid using pencils rated below Blue Wool 5 or with single-star ratings for work you want to last.

See it for real: Manufacturer ratings are a good guide, but nothing beats seeing how the colours actually behave. I've published a set of real-world lightfastness test results for six brands, where sample strips were left in the extreme sunlight of Israel for months. The fading on some "reliable" colours is eye-opening.

Manufacturers Lightfastness Settings

To ensure durability, always check manufacturers' ratings or documentation. For example:

FABER CASTELL (use their own star system) - try to avoid 1 star pencils

Three Faber-Castell Polychromos pencils showing the lightfastness star rating stamped on each barrel

Faber-Castell stamp the lightfastness rating right on the barrel of each Polychromos, shown as one to three stars. These run from two stars (Light Phthalo Blue) to three (Emerald Green and Pale Geranium Lake). Three stars is the top, fully lightfast grade.

CARAN D'ACHE (also use a star system for brands other than Luminance and Museum) - Avoid 1 and 2 star pencils.

Four Caran d'Ache Pablo coloured pencils showing lightfastness star ratings stamped on the barrel

Caran d'Ache's Pablo range carries a star rating on the barrel, one to three stars, rather than the LF1 and LF2 grades used on Luminance. Lemon Yellow here earns three stars; Carmine, Burnt Siena and Sepia carry two. It pays to read the barrel before you rely on a colour.

Luminance ratings are given as LF1 and LF2 - according to the ASTMS 6901 data, LF1 is 100% lightfast and LF2 is 80% lightfast. All Luminance colours can be considered fine for coloured pencil work.

Caran d'Ache Luminance pencils marked LFI and LFII beside a sun symbol on the barrel

Caran d'Ache Luminance carry the grade on the barrel: LFI or LFII beside a sun symbol and the words 'Permanent color'. LFI is the top grade. Every colour in the range is LFI or LFII, which is why Luminance is trusted for work meant to last.

DERWENT (use the Blue Wool Scale) - try to avoid 1 and 2 star pencils. Derwent Lightfast - All the colours comply with ASTMS 6901. The pencils are OIL based (a new departure for Derwent who usually base their ranges on wax or mainly wax and some oil). Softer than Faber Castell Polychromos. An expensive pencil, on a par with Luminance for cost.

Derwent Lightfast pencils marked LFI and LFII after each colour name on the barrel

Derwent Lightfast use the same ASTM grades, LFI and LFII, printed after each colour name. The whole range complies with ASTMS 6901. Shown here: Chocolate and Mid Ultramarine at LFI, Deep Rose and Autumn Red at LFII.

PRISMACOLOR - Sanford have been very coy in the past about publishing the data. However they have now published an official Prismacolor Premier Chart showing the colour card and the official ASTMS 6901 ratings for their 150 colours. They show the range with the 5 grades listed from excellent ( 1 ) to poor ( 5 ). On this scale, the serious coloured pencil artist would normally be aiming to use those in grades 1 and 2 and there are 72 colours Prismacolor Premier pencils that match this aim, with quite a few of the 'good' colours, shades of grey or white.

Ratings vs reality

A manufacturer's chart tells you what should happen. To see what actually happens after months in strong sun, compare these charts against my own brand-by-brand sunlight test results. Some highly rated colours hold beautifully; a few do not.

OTHER BRANDS. Staedtler and Lyra do not publish data on the internet - or if they do, I haven't found it in any leaflets. UV star ratings for Lyra are shown against each colour inside the lid of the box.

TALENS (VAN GOGH) - Talens say that the Van Gogh range 'meet the standards of ASTMS 6901'. I also understand the Dutch made Bruynzeel FullColor pencils are lightfast, but I have no data to back this up.

CRETACOLOUR - Made in Austria by the successors to the Hardmuth pencil business. Colours of the 36 Karmina (dry point) and Marino (watercolour) pencils meet the ASTMS 4303 standard with all colours either LF1 or LF2. Karmina can be very difficult to find, but Marino are on sale in the UK and I have tested them as very good (and not highly priced).

Tips for Protecting Your Coloured Pencil Artwork

Even with high-quality, lightfast pencils, additional measures may help preserve your artwork:

  • Use UV-Blocking Sprays: Apply a fixative with UV protection to shield your work from harmful rays.
  • Frame with UV-Protective Glass: Mount your artwork behind glass or acrylic with UV-blocking properties for added defense.
  • Avoid Direct Sunlight: Store or display pieces in low-light areas to reduce exposure.

Although there is no direct evidence that these help, they are worth keeping in mind.

Summing Up

Investing in lightfast coloured pencils and understanding how to protect your artwork is crucial for creating pieces that endure.

By using high-quality materials, checking lightfastness ratings, and applying UV protection, you can ensure your coloured pencil creations maintain their beauty for years to come.

You might like these

Lightfastness Test Results: 6 Brands in Real Sun

See what actually happened when Prismacolor, Polychromos, Caran d'Ache, Derwent and Van Gogh were left in extreme sunlight for months. The evidence behind the ratings.

Best Colored Pencils for Artists: Find the Right Brand

Which brand suits you? A plain-English guide to matching pencils to the way you work, and to the life you want your pictures to have.

Wax vs Oil Coloured Pencils Explained

Wax or oil-based, which is right for you? Match pencil type to your artistic goals, with UK brand picks from Polychromos to Prismacolor.

Wax Bloom on Coloured Pencils: How to Fix and Prevent It

That cloudy haze isn't mould and your work isn't ruined. What wax bloom is, why it happens, and how to wipe it away.