Tech Talk: Pigments – Week 2

 Lightfastness -- comparing full strength paint

(bottom half is sun exposed strip)

 

Lightfastness -- comparing tints

(top half is the sun exposed strip)

Two weeks ago, I began testing these Mission Gold watercolors. (See the original post here.) After painting the test strips, I cut the page in half and put one piece in my flat files and the other in a spot that would get direct sun. Following my plan to compare the sheets every two weeks, I put the two pieces together today, first comparing the full-strength strips and then the lighter washes.

There are a few changes at this point, although nothing drastic. As might be expected, the tints (light washes) were generally affected more than the full-strength colors.  Prussian blue faded slightly in the tint, as did burnt sienna -- both a bit of a surprise, since the pigments listed on the tubes are supposedly lightfast.  There was also a slight darkening of the yellow, particularly noticeable at full strength. The tint of Van Dyke brown faded slightly.  Neither of these was unexpected -- the yellow pigment was rated as fugitive by both Michael Wilcox and Hilary Page and the brown is unlisted, but its closest relatives are considered fugitive.

It's worth noting that the sun-exposed strip has had only a few hours of sun a day on the best days and we had 4 or 5 days of deeply overcast weather in the past two weeks. I'll continue to monitor the test strips and will post again when there is more information.