As for the sixth layer... not quite so straightforward. I had done a couple of proofs with a minty green which I thought worked, but when I set about the edition, I hated the colour. I mixed five or six different shades, proofing each of them, but not being satisfied with any of them. So I stopped and went home to consider my next move. I don't know if it had anything to do with the fluorescent lights in the Workshop. I'll look at them again in daylight tomorrow when I return to the Workshop.
At the moment I think I might be tempted just leave it at layer five... maybe.