Highlighting and Fading

"Nathan" - thank you for the suggestion, I will try and ask them too, incase there is anything else thats missing, Don explained it very well and I understand now.

Oh ok, That answered my question, so what you are saying is that they (maybe you)  highlight the middle of panels for fading and weathering, not highlighting. Leaching makes a lot of sense thanks very much.

Don pretty much got it. I'd suggest posting in the Armor forum, though. Those guys know what they are doing when it comes to weathering tanks.

There is a forum specifically for painting and airbrushing. It is the one just below this one.  You might get better responses there.

However, one effect the shading folks are trying to achieve, by adding lighter tones to middle of panels, or by pre-shading, is based on the idea that dirt, grease, grime collects mostly in seams and then leaches out over panel from edge inward.