Kath - good to know on the future. Although I was really pleased with the purity seal. It had been sitting for a bit, but it went on smoothly. It darkened the blue a bit and gave it a satin sheen. I'm not sure I would use it on a small mini, but it worked admirably here. As for the black - it's an odd thing. On a small mini you would never just put black on blue. But when airbrushing, as long as you're not too heavy handed (and I was, although some of that was the paint misbehaving), you can get away with it. The nature of the airbrush almost does the blending for you.
Meph - Well you have the advantage not only of time, experience. The missus showed up unexpectedly last night, or I would have gotten the highlights done too!
I'm also a bit stuck on where to go with the weathering. I appreciate the work you and GD did with salt and the metallic undercoats, but in all my fluff reading the first thing marines do when the get back on the battle cruiser is send the armor off for repairs and paint. They also spend a lot of time polishing the stuff. So the idea of a corroded, rusty, worn down marine just doesn't sit with me. The only wear or damage would have to be quite recent. So I need to find a way to make it lived in, without making it look neglected.