My previous post showed a finished painting drying in the sun. Actually, painting on a canvas that has sunshine on it creates a very strange painting when brought indoors, sometimes it is positively garish and other times it is incredibly dark. It took me 3 ruined paintings to learn to ALWAYS have my canvas and my palette in shade. Therefore I bring a 60" artist umbrella to our paintouts as well as choose locations with abundant shade trees or overhangs. Standing in sun for hours, sunblock or not isn't a healthy practice either.
It helps to have a good sense of direction or a compass when plein air painting. In this case, I put a straight edge on the ground at the edge of the shadow and watched to see the sun move over the marker-it only takes 2-3 minutes to plot a good spot.
photos by Bobbie Peters