HOW I PAINT METALS
(using metallic colors)
Being a painter obsessed by Dwarves, since the beginning of my journey in the valley of colors and brushes I had to paint a lot of metallic surfaces: after all, mighty weapons and armors are in general 60% of a Dwarf figure, and we love them for this reason!
There are many ways to paint metallic surfaces using metallic colors: if you are a novice, you will learn that just base+wash might give you unexpected results.
On the armor of this Primaris Marine, for example, I've just airbrushed a mix between Vallejo Metal Color Chrome (approx 90%) and Vallejo Metal Color Jet Exhaust, then I washed it with Nuln Oil Gloss. The quality and inner reflection of the metallic pigments of this Vallejo line do all the lights and shadows work: it's almost magic!
However, for my Iron Crow Sentinel I wanted to experiment a more elaborate technique, to have a more textured finish: I tried to paint my metallic surfaces with the stippling technique.
Before going on, I want to premise a bit the ideas behind my approach to metallic colors. As you obviously know, the most important difference between a metallic pigment and a "normal" one, is that the metallic pigment has an inner ability to reflect light. For this reason, I think that metallic colors are very interesting because they allow you to paint contrasts on (at least) three different levels: brightness/darkness, saturation/desaturation and shine/matt.
When I paint metallic surfaces, then, I always try to push the contrasts as much as possible, making not only (obviously) the lights brighter than the shadows, but also working with highly reflective lights and matt shadows.
To paint the metallic surfaces of this Iron Crow, I've started as usual with a homogeneous basecoat, in this case a pure Citadel Chainmail (1). Obviously, you can use any color you want.
I think that, more than with normal colors, it's important to take your time to achieve a perfect, uniform, basecoat: metallic colors could be tricky to paint "smoothly", because if you don't get attention to their dilution, you might easily have a lumpy surface. This is not a mistake, or better, not necessarily: if you want to paint a metal surface that you imagine to be old and rough (a Skaven/Goblin/Orc etc etc character, maybe?) adding a 3d texture directly to the surface might be interesting.
However, I normally try to achieve a smooth and uniform basecoat, that allows me to better work with the other steps.
So: now that we have a smooth and bright surface, let's ruin it! With the never-too-blessed Badab Black (the grandfather of Nuln Oil, another great line of colors that GW decided to obliterate...) I try to give a first, rough texture to the area (2). Here, you don't have to be surgically accurate, but have fun and try to give your metal a first shading and a rough texture. If you are wondering the exact brush strokes that I use in this step, I just dip the brush in the pot, and then I try to create several puddles of wash on the surface. I try to avoid that the wash just flows into the recesses, instead I want it to "stain" the surface. Exactly the opposite work than a normal wash. I love the Badab Black cause it is more thick than normal wash and has an almost matt finish, that allows me to have immediately dark and matt shadows. If you only have a Nuln Oil (or equivalent), I think that adding some matt medium could help you to find a kind of good replacement.
Now, after the wash is completely dry, I start to build my more accurate texture, using again Chainmail (3). The dilution here is approx 60% water and 40% color, and I paint using the stippling technique. In brief, instead of trying to paint smooth layers, with stippling I use the tip of the brush and I paint tons and tons of dots. In this video, you may see a good explanation of this technique.
"Ok, but how do you smooth layers, with stippling?!" Obviously, you can't (and don't want!) to have perfect and smooth transitions, when you paint with stippling, but in general I always try to be clean when I paint, even if I'm texturing (it's a kind of obsessive compulsive disorder, I know). To smooth a bit the transitions with stippling, I simply paint dots using the brighter color (so if I want to smooth a transition between Chainmail and Boltgun Metal, I use Chainmail dots), but more diluted than normal. In this way, the diluted color, with its transparency (due to dilution) will create a kind of mid-tone that will soften the transition.
Obviously, you can also make the opposite way, using a dark color (for example, a very diluted black/brown ink), but in general I prefer to work with bright color on dark surfaces, than the opposite.
You can see how it looks the texture after a bit of "smoothing job": here, I use very diluted dots of a mix between Scorched Brown and Black to darken the Chainmail dots below the blade edge (and to increase shadows in general), and diluted Chainmail dots to increase lights on the edge (4). If you see, in this step I also start to build some minor shadow, for example I darken a bit the middle of the edge, to give a more interesting and "metallic" look. Basically, I work as I'm painting with a NMM technique, but using metallic colors.
Before proceeding with further lights and shadows, however, I give a subtle layer of matt varnish, using my airbrush. I know that it seems a kind of sacrilege ("you're ruining the shine of your lights!"), but let me explain better: I want my texture to be readable. Being metallic pigments highly reflective, if you want to highlights (for example) a Chainmail with a Mithrill Silver, you almost lose the texture, because at a certain point, the shine of the bright metallic colors will visually "merge" the various dots, and you won't see any difference or the pattern of the texture. Or at least is what I perceive.
For this reason, when I start to paint the lights, I alternate dots of more and more bright color, with subtle layers of matt varnish: the matt varnish turns off a bit the metallic pigments, allowing you to see the texture even when the color is really bright.
After this process, I decide to give some hue variations to the metal, adding a subtle yellowish glaze to the edge of the blade, made simply with Vallejo Transparent Yellow (and a bit of Vallejo Transparent rRed, just to avoid a neon-yellow effect) (5).
I now work to define better the texture, using tiny, highly diluted dots of Scorched Brown and Black to increase shadows where I think they should be darker (for example immediately below the edge, to increase the contrast), and diluted Mithrill Silver dots to increase lights (6).
The final step is, at least for me, fulfilling, because I paint the brightest lights to achieve the most contrast possible (7). In specific, I use Vallejo Metal Medium, that is almost the metallic version of pure white. Don't overdo with this last step, but just focus on a very small area, in order to maximize the contrast and creating a focus-point.