Lightfastness test

I’ve been a busy bee this summer: I was testing pencils and watercolours in the sunlight!

During the next weeks, I will be publishing here the results of my LIGHTFASTNESS tests.

Lately I’ve been thinking a lot about the materials I use and their resistance to light. When working on a piece with the intention of selling it, this was not even a question, I always work with materials that are guaranteed by the maker to be light resistant. I also take all the necessary steps to ensure the longevity that an artwork deserves.

When I’m relaxing colouring or sketching, I use coloured pencils and watercolours and never really considered their light resistance. After getting more involved in colouring, seeing the beautiful work people create and spending hours completing a page, it seems very important.

How long my work will resist? Is it ok to frame my colouring or will it fade when on the wall? Some pigments, in presence of light will start to fade. Lightfastness is the capacity that some pigments have to keep the intensity of colours even when exposed to light.

In my tests I’ve found out that some colours will completely disappear after only 30 days of light exposure, all erased by sunlight. Below there’s an example:

———-↓Covered           ↓Exposed to sunlight


The first column was covered, protected from light. The second one was exposed to sunlight.
Other colours will completely change, Purples will became red, blue or brown. Greens will go yellow. Reds will become orange.

Some pigments are so bad that even the part that was covered changed too. Here’s an example, those are the SAME two colours 024 and 041:

                 ↓↓Never been exposed to sunlight             ↓Sun but covered    ↓Full sun exposure


The first one is before going to sunlight, the second shows that the column that was covered shows great alteration in the pigment, and the column that was exposed to light simply disappeared!!!

I must confess some results did break my heart…:( Some brands that are accessible and that I really like to work with were a total disappointment concerning fading. Some colour just disappeared.

Which brands were tested?

I’ve tested mostly student pencils, because those are the ones I’m very curious about. Is it really a good deal being cheaper if the colour will be gone within a few months?

Besides that, most artist pencils makers are proud to exhibit their lightfastness rates. There is no point for me to be testing Faber-Castell or Caran D’Ache products, because they have been tested by professionals and this information is available and easy to find, even printed on the barrel of each single pencil.

I specifically wanted to know about Arteza, Guang Hui, Castle Art and other budget friendly pencils, because those makers don’t say anything about light resistance.

My tests are “homemade” and even if I’ve tried to follow a method in order to obtain fair results, still not a laboratory test in controlled conditions. Although I believe my results are pointing in the right direction, I’ve done this to satisfy my own curiosity and my results are only a general view, not a detailed scientific analysis.

If you are interested in learning a more scientific perspective on lightfastness tests and brands ratings, the CPSA – Colored Pencil Society of America offers the CPSA Lightfastness Test Results Workbook, a publication available in PDF format for paying members. I am not a member, so I can’t comment on the content, but CPSA is a serious, respectable source for artists that work with coloured pencils.

Arteza test
Crayola Twistables test
Schpirerr Farben Test
Castle Art test
Marco Renoir test
Guang Hui test
Prismacolor Premier test
Irojiten test

What happened? How colours perform?

In my tests I’ve noticed a pattern for some pigments:

Pinks are the pigment that demonstrated more sensitivity to light. In other words, the worst. No resistance to light at all, even if covered.
Pinks will simply disappear from the paper. No mercy 😦

-Followed closely by purples: Oh! The ever changing purples…
Most purple pigment will show big alterations in tonality. Purples became reds, browns and blues. Changed colour even when covered.

– Most reds and dark reds faded. Skin colours too.

-Many ochre pigments showed changes in colour after 30 days of sunlight.

Yellows, Oranges and Orange reds showed good resistance to light.

-Most blues demonstrated good to excellent resistance to light. Most were not altered by sunlight. Blue tonalities that showed changes were the warmer blues or lighter blues ( I suspect the ones with magenta or similar pigment in composition).

-Most greens behaved well after sunlight exposure, with the exception of olive greens that became lighter.

-Most greys, darker browns and blacks did not had any alteration in tonality after exposure.

Testing methods

1- Fill a colour chart with two columns.
2- Cover one of the columns with paper and tape.
3- Place chart placed with tape on a window, from inside. ( In my case, the window is facing west and receives up to 7 or 8 hours of direct sunlight during summer months.)
4 – Wait 30 days.


  1. This is so very interesting and I would love to have it available for my coloring group to read. If you would like to pop over to LizatHome on Facebook and share this page, I would be really pleased, otherwise if you could give me permission to share it please.

    Liked by 1 person

    • Hi Liz, I’m happy you liked the post and found it interesting! I’ll be sharing at your Facebook page, but please feel welcome to share everything you want. My purpose with this blog is to exchange information and learn a bit too. Cheers!


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