Should I consider lightfastness scale while choosing artist grade watercolor?

Question

I just started to use watercolor and got a set of 6 Schmincke Horadam watercolors. I decided to get some more and looking at a color table I found out that colors have a lightfastness categorization.

I thought that all artist grade watercolor was at top of lightfastness grade.

However, it says "The rating of lightfastness as a 5-star-system is based on blue wool scale. This allows a more precise differentiation especially in the more lightfast categories."

Few colors have a 1/2 star on lightfastness scale and some new colors have "Without evaluation of lightfastness."

Should I consider the lightfastness star when choosing color or bottom line is more than enough?

What's the minimum star rating I should look for to make sure it has durability over time if kept indoor and not direct sunlight exposition?

Here is a link to the color table with lightfastness stars.

Answer 1

Watercolor is especially susceptible to fading under light. This can be explained by the binder for watercolor and the way watercolor is used. The binder is usually a mixture that contains mostly gum arabic. Due to the usage of watercolor in thin layers the binder will not be able to coat the pigment properly leaving it exposed to light. Lightfastness should therefore definitly be considered when using watercolors. However, it depends on your aim for your drawing.

If you only want to practice to get better at watercolor you might want to look at inexpensive watercolor pigments that might therefore lack in lightfastness. Those works can still be durable if kept in a dark environment such as a folder. Displaying paintings with colors of low lightfastness will result in quick fading (a hint at how quick the fading will appear is given in this table). If you still want to hang a drawing in a well lit place you can use Aquarell-fixatives to improve lightfastness. Those Aquarell-fixatives or finishes come as a spray and allow to apply a UV protective layer that also protects from dust, moisture and other bad influences. Going one step further you can also frame your image behind UV-protective glass to ensure longevity of colors.

On the other hand, if you plan to display or sell your drawing (from the beginning) you should opt for the (more expensive) lighfast pigments and take the above measure in addition.

Answer 2

The professor for my watercolor class in college said she always does her own lightfastness tests for any new paint before she uses it in any painting she's going to sell.

As it turns out, it's pretty easy to do your own lightfastness tests. Paint a series of broad lines on a sheet of watercolor with undiluted color at one end of the line and gradations down to a light wash at the other end of the line. Let this test page dry completely. Take a scraps of mat board or card stock and cut them into strips. Place the page on a windowsill of a well-lit north or south-facing window and cover half of each line with a card strip, leaving the rest of the line exposed to the sun. Keep the page on the windowsill undisturbed for a few months. Then remove the strips and look at the lines on the page. Judge for yourself what colors are fugitive and what ones are worth using.