Colouration & Rusting

I've got a book out the library called 'The colouring, bronzing and patination of metals' by Hughes and Rowe. Much of the content isn't relevent to me now, but one idea stands out as perhaps worth trying. They call it Particle/Sawdust Technique. Basically it means using sawdust or wood shavings or something similar to keep the surface of the metal moist and allow oxyidisation. You can also pigment the surface with this technique. Maybe I could get sawdust from the technicians and immerse a cast using this..