I made an outline drawing of the major shapes of the pipes and cogs. I did not make a detailed drawing as my intention was to use the paint to paint in the smaller details.
My palette was a variety of different mixes made up of: perylene maroon, perylene blue (for the purple colours) in varying degrees of each colour, Indian red and burnt Sienna for the rusty colour.
I painted in the main body of pipes and cogs firstly. This took a while as I was working in glazes, and there are 5 or more glazes on most of the shapes. I wanted to achieve the darkest of tones of each of the colours I mixed. This was necessary to make the 3D effect, separating the pipes and cogs from the background.
I painted in the background using lighter tones of my premixed colours.
The final stage of this painting was to outline the pipes and major shapes with the darkest mixes of my purple.