He's taken long enough to do, mostly because of the near complete repaint when I decided that I really wasn't happy with my old style of painting bone. Which as you can see was working from a base of bubonic brown and building up to a pale highlight, but the overall effect was too yellowy for my liking and didn't have the coldness I wanted of my bone colour.
Now I confess the old style attempt was largely the result of the paints I had at the time and relearning how I used to paint Deathwing as a lad, almost 20 years ago. A lot has changed since then, the main thing being that I have the cash to not have to "make do" with the paints I have. Plus the world of paints has moved on as well and I'm not limited to what Citadel has to offer me. Since my friend Wayne introduced me to Reaper Miniature Master Series, in particular the bone triad, I really have't looked back.
The painting of my first landraider using the reaper bone triad and my new Badger 500 airbrush was something of an eye opener. I loved the bone effect achieved with the triad and it needed to finish it off was the P3 Formula Menoth White from Privateer Press to edge the highlight (a superb offwhite colour for bone and also an excellent paint). Which isn't to say that the overall colour schemes are so radically different that I can't field them in the same army.
I might tweak the soot from the ejection port for the assault canno, to have a more intense scorch mark nearer the port, but otherwise I'm pretty happy with it.
On the red detail of the dreadnought I did the final highlight by using a technique Ron posted on FTW about painting Flesh Tearers. I used bleached bone as an edged highlight as Ron did and washed with Baal Red. I'm quite pleased with how it turned out.
I slightly changed how I did green as well. I still used Dark Angels green as my base, followed by a black wash. However, Snot Green for my highlighting was too bright. To get a darker highlight, I mixed Knarloc Green with DA Green (approx 50/50) which gave me an effect I was happier with.