I don't know about 'two toned method' I just know that I used a contrasting color of paint to bring out the raised portions and the edges.
On painted metal chipping and wearing of the paint starts on the edges and the raised portions, The streak effect was an accident, too much paint on my brush, I decided it looked good so I kept it. Plus, it works just fine...I can't wait to get ahold of a long shot to paint Mmmm Mmmm