Painting A Slipper Orchid

My Slipper Orchid has bloomed again this year and has the most amazing large flowers. I sketched a couple of compositions but settled for the front and back view of the plant shown below. Please excuse the colour of the paper as I had to enhance the image to show my pencil drawing.

I decided to use Sennelier paints. They have a very creamy feel and I am using them more and more.  I mixed Cadmium lemon yellow with Ultramarine deep to obtain the green for the back petals and a weaker slightly more yellow mix for the outer petals. 

I then mixed Cadmium yellow light with Cadmium yellow orange to apply a wash to centre of the flower and the slipper shaped petal. I then began building up the markings on the outside and the slipper shaped petals with a reddish brown mix made by mixing Carmine genuine, Cadmium yellow light and Ultramarine deep. The outer petals were dampened with a wet brush and left until there was just a slight sheen, before the colour was applied, following the pattern on the petals closely. If a hard edge appeared it was softened with a slightly damp brush and, before the wash completely dried, I removed the highlights with the brush. The slipper shaped petals were again dampened and the colour applied. I lifted the highlights from the right and left side and a little from down the centre. I loved painting these first stages but by the time I had progressed this far the sun was low in the sky and it was time to stop.