This may be useful for those of you who are painting with White Nights watercolors. Many people claim these shouldn’t be used for serious artwork and that they’re fugitive and student quality. So I did a lightfastness test with quite amazing results.
The exposure to direct sunlight took almost 4 months (14. 5. - 9. 9. 2014). The paper used was average quality Fabriano, 25 % cotton. The top of each gradient was exposed while the bottom was covered with black cardboard stripe.
My set consists of approx 40 colors of which 4 I’ve thrown away already. From the 36 colors 31 show no change, 2-3 show very decent change and 2 show more significant change. No. 216 and 320 are more fugitive, 216 being a mixture of pigments and 320 persian orange which is supposed to have ASTM rating II and thus I believe the manufacturers probably made a mistake or something. 312 also shows a decent, almost invisible change. 312, incorrectly named Vermillion, is a mixture of hansa yellow and aniline red which is fugitive (ASTM II-III).
Another color shift can be seen on 608 and 607. I was unable to see this on the paper but the scan revealed a slight shift towards red with 608 and a decent desaturation with 607. These two violets use purple and methyl violet pigments (ASTM III-IV). But still very good result. I miss dioxazine and cobalt violet here but I can see why these are not being manufactured by White Nights. Cobalts are relatively expensive pigments.
The bottom row doesn’t have numbers but from left to right they are: raw umber, burnt umber, sepia, payne’s gray, ivory black, voronezhskaya black.
I wouldn’t be really afraid anymore to use these as all you need to is to avoid fugitive colors, try to mix oranges from cadmiums and purples from blue and green. The way I see it, the other colors seem pretty safe. But maybe longer exposure to light would reveal something else. Who knows. :]
The manufacturer’s color chart with actual color names and pigments used can be found here: http://www.nsp-enterprises.com/WatercolourWhiteNightsChart.jpg