Here are the other half of the power-armoured Grey Knights, and the last of a nice little commission. There are currently no marines on the project table, but I am sure that will change soon.
I like painting marines, they can get done fairly quick and they look good as a cohesive force. The only time consuming part is the armour, and then it is just purity seals and details for the most part.
I've done these Grey Knights' armour as simple as possible (being a table top quality job). I started with cold steel (P3), washed with drakenhoff nightshade (gw), and highlighted it with chainmail (gw).
Once they were all ready, (and pictures were taken), I sprayed them with purity seal (gw) which dulled down the metallic effect to an agreeable level. I gloss varnished all the blades and plasma coils after the spray.
It is entirely likely that there will be more GK's in the future, fate will tell...