Base: very old GW orc brown - lovely color :D
Then a wash of GW serpia
Next step was a skin drybrushing
It was then time to work some other colors into the skin, so he was given a random stippeling with a dark brown color and orange as well. Needed plenty as the next step would cover up most of it.
Another lighter fleshy drybrush.
Then I worked in some shading by adding ogryn flesh wash to "under sides" ie. non light exposed parts of muscles and fattybits. A purple was was added in the deepest recesses and in random patches to add even more depth to the skin.
Orange wash was applied on recesses and around implants/rusty bits.
Top layer drybrush of the skin - quite light coat of drybrush.
Finishing touches included picking out details and adding purple, orange and reddish washes around implants to make the skin look more irritated.