I have been thinking about the paints I'll use for their black armor. There are a lot of tutorials and how-to's online about how to paint black, each uses a different variation on the theme. Some rely purely on a black paint with grey or blue highlights. Some use grey shaded with black, and some even attempt an NMM (non-metallic metals for those who don't know) effect.
I've only painted black armor twice before, both times for Ultramarines Chaplains. For those models, I used a deep, dark grey from Reaper call "Grey Liner." Basically, it's a paint designed for darklining fantasy miniatures. Darklining is where you paint a thin line of a darker shade between two separate pieces of a model, like a flesh-colored arm and a tunic sleeve, or an armor plate and a leather strap or belt. I think this is an outdated technique that most folks don't use anymore, having been supplanted by washes, but I could be wrong.
Anyhow, this paint is a very dark grey. For my Chaplains, I primed black, applied Grey Liner to all the armor, and then edge highlighted with lighter greys. Here is what it looked like on my counts-as Chaplain Cassius (try to ignore the horrible posing of the model):
Here's another shot with less colors, so you can compare it to the basic black of primer:
I think this paint scheme will work for Raven Guard. However, my Raven Guard will be very plain in the armor department. I'm planning to select a lot of models and parts that don't have a ton of dangly decorations and fancy parts. I just don't see Raven Guard, the sneakiest of sneaky, carrying around all that junk on their armor. The clink of a decorative chain can give you away, and too much carved decoration on armor makes it harder to slip through small areas. The issue facing plainer armor using my Grey Liner method is that the models might be too plain on the table, looking like unpainted, primer-only models. My hope is that the edge highlights, small metal or colored details, and deeper black of a Badab Black/Nuln Oil wash in the recesses will help them stand out enough to look properly painted.
One additional idea I'm thinking about is switching over to GW paints for Raven Guard. The only problem is, I have no idea if they have an appropriately dark grey to replace the Grey Liner. I know I'll be using Leadbelcher and Ironbreaker for metal parts, plus Nuln Oil as a wash. While I do want the models to be muted and dark, I don't want them to be boring. The solution to boring black armored models is to add small splashes of color here and there. Grenades, pouches, and especially bolter casings. The bolter casings for my Ultramarines are black. Black casings over black armor will be too monochrome, so I'm thinking of using a very dark tone washed with Nuln Oil for the casings instead. I had my eye on Incubi Darkness for a greenish blue undertone, but I have no idea what the paint looks like in person. The other option is Caliban Green. Does anyone use these colors and able to tell me how they'd look slathered in Nuln Oil?