Light-fast Testing Shinhan Watercolors (PWC)

      I usually have watercolor paper trimmings lying around as leftover from making a sketchbook. Just for fun, I've decided to swatch my favorite color from Shinhan and do a light-fast test. I did this by painting a gradient wash on a strip of paper about 5" x 1.5"  then cut it lengthwise so that I have an identical strip. I then taped one strip on my window and kept the other one inside an envelope. A month has passed by and comparing the 2 strips, I was surprised that there is no difference. No fading, no discoloration. I'm aware that true light-fast testing takes a minimum of at least a year, but just the same I expected some result since my window is in direct sunlight from 11am to about 5pm.
     This encouraged me to do a test on all the Shinhan paints that I have so I made a swatch as seen below :

 Here is the swatch before it was cut and exposed. 7.5" x  5.5" 300g Arches CP