I remember researching the effect at the time, but to be honest have quite forgotten how I came about the decision, so unless I wrote it in the post........,
HOWEVER...I can link you to the pages where I did the work, and for my own use I always include the colours I am using ......so I too can go back and check it out LOL......
Luckily it was one of the first things I did after Kal started the thread
page 4...... post 95.........kals crane
"http://www.rmweb.co....-4#entry1069380"
shows the colour, and several posts cover the build. People had not asked me at that time to cover each step.....so it will be a bit choppy. The yellow might not look right...BUT it will be the one I used. And as it is in the airbrush booth....I obviously mixed airbrush and hand work. The citadel transparent colours would have been added last, and the rail match opaque colours added first.
Having just look at page 5, I do remember I thinned the paint to go in the airbrush, and found i had to do several layers, and like the effect of the plastic showing through underneath led me to only adding a few layers of yellow be I started the weathering. Have a look and if you have any question after I'll see if I can clarify.