oadie wrote:
Looks like you want something like the old GW Scorched Brown (I use the Vallejo Game Color equivalent, Charred Brown). Nice and dark brown, slightly on the warm side. Too stark a jump to go from Scorched to Bestial directly, if you want to use it for highlights, but the two play nicely together, if mixed.

Not sure about the black iron paint. When I want the subdued iron look, it's usually in smaller areas of weathering, so I just use a soft pencil. Graphite over black paint is still an option, it would just require grinding up a bunch of pencil leads or buying an iron pigment to cover larger areas. Black ink over silver metallic paint is another way to do metallic black, but it doesn't look much like iron, in the end - graphite has a nice dark silver color and a low, even sheen that can't be beat, in my opinion.

Drybrushing doesn't take much in the way of special equipment, luckily. People usually keep dedicated brushes for it, since it's hard on the bristles (in fact, most larger brushes that would get retired, due to splaying bristles and the like get relegated to drybrush duty, instead, as you don't need a fine point) - flats or filberts are more popular than rounds, due to their increased coverage. Bristle qualities are debatable - some people prefer shorter, stiffer bristles (which make it easier to scrub the paint off), while other prefer something softer and finer, like a makeup brush (which allows for a finer, smoother dusting of pigment). The technique works, albeit slightly differently, with just about anything, though - I've used stiff hog hair flats, bushy old nylon brushes, and soft Taklon filberts, all successfully.

The technique is pretty simple, at its core - load your dry brush with a bit of undiluted paint, then scrub it on a paper towel. The goal here is to remove most, but not all, of the paint, leaving only a little half-dry pigment and binder behind on the bristles. The brush is then lightly swept across the area in multiple passes, depositing pigment bit by bit, primarily onto high points of the surface. If the surface is highly textured (where drybrushing really shines), you'll get super easy and reasonably smooth highlights. On flatter surfaces, the texture that picks up pigment is simply that of the underlying coat, so you get a more general, chalky or dusty appearance.

The real key to drybrushing is brush load. The more paint on your bristles, the starker the effect and the more likely you are to leave streaks. For a subtle effect, you need to make dozens of passes (which doesn't take nearly as long as it sounds) with barely any paint on the bristles, building the effect gradually. There are sometimes cases where you want more paint and a coarser effect, of course - this is sometimes referred to as overbrushing, which applies a thicker, more solid looking coat (due to having more paint on the brush), but still remains mostly on raised surfaces (due to the light sweeping motion and low flow of undiluted paint).