Ian, looks great so far. As you mentioned and I was going to ask, is that the rust or the red-primer showing through? If it is the rust you could tone it down with a light wash of raw umber...or is it bunrt sienna?.....the dark brown is the color I am referring to. I ALWAYS get those two confused....

That would take the vividness out of the orange.... Just my .0175 cents worth. Looks great so far. Looking forward to the finished product. "Q"