Painting the skies in a plein air piece is one of my favorites. With oil pastels one can capture the fleeting impressions of moving clouds and changing light. This is a little exercise to demonstrate some of the basic methods I use en plein air.
My standard set for oil pastel studies is a 48 colour Caran d’Ache oil pastels set, that I keep as a kind of fresh stock with me. I break the oil pastels in smaller pieces before I use them. Those pieces in use are kept in a separate card board box that I place on the left from my painting support which is fixed to piece of 6 mm plywood with two clamps. While painting I put the colours used in the actual painting on the box lid of the opened box. That sorting helps to keep at the colour scheme that I have chosen.
Starting with a colored support
I always have a fairly large stock of oil colour primed papers either from misprinted monotype prints that I enhance a bit with some more oil colour, or papers that I have used as protection for my working table or papers that I prepared with purpose as support for oil pastel paintings.
Mostly I try to do cover the sheets with free abstract brush strokes, but it can happen that I decide to do an under painting in suitable colours. In this case I used a sheet of ca. 6×8 inch that was covered already in a mix of blue and grey colours very similar to the looks of the sky on that day I went out.
Before going in detail with the sky I quickly sketched the distant green and red, brown fields and a group of trees with some bushes. I had put down a layer of black oil pastels in the shape of trees before using some greens in the tree tops and bushes to mute down the green in order to get a similarly strong contrast with the sky as observed in nature.
To find out which colours might go best with the sky and the support I played around a bit with some colours. At first I liked the violet on my support and tried to use that in the colour theme, but it did not fit as I expected so in the final picture there is only very little violet to see. The main colours I used for the sky were light blue and turquoise blue, in addition to that light beige (from the 96 colour set) and grey were important colours.
I used a rubber blender or shaper to blend the colours and to form textures. Depending on the colour I intended to end with I either started with a blue and added brighter colours like white or the light beige on top (for light blue) or I started with a layer of white, light grey and some blue would be in the final layer for slightly blue clouds or sky patches.
For the clouds I start with the pure white as I want to keep the top of the cloud in bright white. I might add some beige and or light and darker grey to the lower body of the cloud for the shadows in the clouds.
The clouds moved fast on that day, which was not a big problem as I could choose from many different clouds in all sizes and shapes. It was not necessary to depict that one specific cloud instead of grasping the typical features of the clouds in the sky in that hour of an unfortunately rare day with sunshine this spring.