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Postby Celtic Lass » Fri Sep 23, 2011 2:08 am

I was curious about the lightfastness qualities of the watercolors I have invested in and am using. I keep reading opinions that colors that have "hue" in their name do not have good light fastness. I have also read some back and forth opinions regarding some colors such as Aliz Crimson.
So I decided to do my own lightfastness test for the two travel size watercolor kits I have. I painted a one inch stripe of color on Strathmore cold press 140 lb paper 10" x 7" sheets. I covered 1/2 of the color stripes with heavy black construction paper. I left the pages out in the sun for one month. They got approx 6 hrs of direct sunlight at (nearly) sea level and 6-8 hrs of indirect light.

Winston-Newton (my kit holds 12 colors- I tested 21 colors as I have added to and deleted some of the original colors to personalize it) They are all artist quality NOT the cotman quality pans. Only three colors faded just a bit:
Payne Grey, Purple Lake and Ivory black.
These colors remained fast: Cerulean blue, Cobalt, Ultramarine, Burnt umber, Burnt siena, raw siena, Hookers Green, Olive green, Viridian, Sap green, Aliz crimson, Perm Carmine, Cad Red Deep, Vermillion, Cad Yellow, Cad Yellow Deep, Lemon Yellow, & Yellow ochre.

Koi 24 color kit- These colors faded (some pretty badly):
*Ultramarine, Prussian Blue, Olive green, Aureoline Hue, Perm Deep Yellow, *Perm Orange, *Jaune Brillant, *Crimson Lake, *Purple. (the colors with the *'s faded the worst)
These colors remained fast:
Cerulean blue, Yellow Green, Viridian Hue, Perm Deep Green, Yellow Ochre, Light Red, Burnt Umber, Paynes Grey, Ivory black, Lemon Yellow, Vermillion hue, Cad Red Hue, Quinacridone Rose, Cobalt Blue Hue.

I realize that most of our sketches will remain safely away from direct light, but I think I will find myself using the Winston-Newton colors more because of this test.
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Celtic Lass
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Postby mdmattin » Fri Sep 23, 2011 1:44 pm

Celtic Lass,
Thanks for doing this research! I often wonder about viability of "undocumented" paints that come in ready made kits and paint sets. Most reputable suppliers these days list the chemical names and pigment color index numbers (PR108 = Cadmium Red, for instance), but some suppliers keep this information secret.
Are you familiar with the Handprint site? Bruce MacEvoy has created an incredible resource for watercolor artists, which I find myself referring to on an almost daily basis. One section is aguide to pigments, which lists all of the major pigments by color index number first, then by the formulations of different paint manufacturers.
Each paint is rated with quantitative measures of lightfastness, staining power, and other attributes, as well as information about its interaction with other pigments, handling properties, etc.
MacEvoy encourages artists to do their own lightfastness testing, as you have done. I admire your patience and perseverance - I would probably forget all about what I had done and wonder years later what all that faded looking paper by the window was all about.
It's not the case that "hue" in the name necessarily indicates unreliability. It could just mean that color is made by combining different pigments to match or approximate a traditional color for which the original pigment has become too scarce, is too toxic or has itself been shown to be fugitive. However, the safest bet is to buy paints based on a single, identifiable pigment, which you know to be lightsafe.
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Postby Studio-1-f » Fri Sep 23, 2011 2:11 pm

Good for you for doing your own tests! You can also find ratings on the manufacturers' sites.

Here is the Winsor & Newton Artists' Water "Colour" Composition & Permanence chart. See the "Permanence" column on the right:

Here is one blue chart from Graham's. See the "Lightfast rating" in each color's info box:

Here is the DSmith chart. See the "Lightfastness" column, in the middle:

I can't see anywhere on the Sakura site where they make any permanence or lightfastness claims whatsoever for the Koi watercolors:

To tell the truth, I am not much bothered by issues of lightfastness (who the heck is gonna care in 100 years?) but I do like to give myself every chance to succeed, so try to buy the best stuff that I can afford. Hence, I stick to W&N, Graham's, and especially DSmith. Love DSmith paints.

= Observe Closely
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Re: Lightfastness

Postby BeginAgin » Sat Nov 05, 2011 9:40 pm

Thanks, Celtic Lass, for the lightfastness tests.
And thanks, Jan, for the links.

Been away because of eye problems and
return to this helpful new format that is
much easier on my eyes. So thanks, gpathy,
and Russ, for that.

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