Plein Air Painting: Lessons by Eileen Murphy. Plein Air Oil Painting Workshop at Wethersfield Garden, 1:00-5:00 pm. $95.00 One day plein air oil painting workshop at the beautiful Wethersfield Garden in Amenia. This class is open to all levels and will run from 1:00-5:00 pm. Students will be guided through approaches and techniques of color mixing and brushwork. Discussions on composition, value, color, edges, aesthetics, atmospheric perspective, and simplification and massing will also be offered.