Quick answer

Thin Citadel Contrast paint with Contrast Medium, not water. Water breaks the surface tension and causes the paint to pool unevenly, ruining the shading effect. Start with a 1:1 ratio of Contrast paint to Contrast Medium on a palette, then adjust: more medium for a softer, more transparent glaze; less for a stronger, more opaque layer. Always test on a spare model or a primed area first.

Why water is the wrong thinner for Contrast

Contrast paints are engineered to flow into recesses and stain raised areas in one coat. Their magic comes from a delicate balance of pigment, medium, and surfactants that control surface tension. Adding water dilutes that balance, causing the paint to bead up, dry with tide marks, or lose its ability to shade. Contrast Medium (sold separately) maintains the same acrylic medium and flow properties, so you can thin the paint without breaking its behavior. If you must use water, limit it to a tiny drop on your brush for smoothing edges, not for mixing into the paint.

Choosing the right medium and tools

Citadel Contrast Medium is the only medium specifically designed for Contrast paints. It is not the same as Lahmian Medium, which is for thinning regular acrylics. For airbrushing, use Citadel Air paints like Vulkan Green instead of thinning Contrast, as they are pre-formulated for spray. When hand-brushing, a wet palette helps keep your mix workable, but avoid over-thinning; Contrast is meant to be used fairly thick. A dedicated pipette or dropper makes measuring ratios consistent.

Step-by-step: thinning Contrast paint correctly

  1. 1. Shake the Contrast pot thoroughly: Contrast paints separate quickly. Shake for at least 30 seconds until you hear the mixing ball rattle and the paint looks uniform. Skipping this step leads to inconsistent thinning and poor shading. Checkpoint: No streaks or clear medium at the top of the pot.
  2. 2. Place a drop of Contrast paint on your palette: Use a dropper or the pot's nozzle to dispense a small, controlled amount. A little goes a long way; start with 2-3 drops. If you use a wet palette, be aware it may already add moisture, so you might need less medium. Mistake to avoid: squeezing out too much paint; you can always add more.
  3. 3. Add Contrast Medium in small increments: Start with a 1:1 ratio: one drop of medium for each drop of paint. Mix with a clean brush. For a more transparent glaze, add another drop of medium; for a more opaque layer, add less. Stir gently to avoid bubbles. Checkpoint: The mix should be smooth and flow off the brush without being watery.
  4. 4. Test the consistency on a primed surface: Brush a stripe onto a spare primed model or a piece of plastic card. The paint should flow into recesses and leave a thin, even stain on raised areas. If it beads up or looks patchy, add a tiny bit more medium and retest. Mistake to avoid: testing on your actual model first; always use a test piece.
  5. 5. Apply to your model with a single, confident stroke: Load your brush but not too much; you don't want puddles. Apply in one direction, then leave it alone. Overworking the paint while it dries will destroy the Contrast effect. If you need a second coat, let the first dry completely. Checkpoint: The paint should self-level and dry with smooth shading, not streaks.
  6. 6. Adjust ratio for different effects: For a subtle tint over a light base, use 1 part Contrast to 2 parts medium. For a stronger shade on larger areas, use 2 parts Contrast to 1 part medium. Keep notes on your ratios for future projects. Mistake to avoid: using water to adjust; always use Contrast Medium.

Products that make thinning easier

  • Citadel Contrast: Briar Queen Chill: Citadel Contrast: Briar Queen Chill is a Contrast paint that, when applied over a light Contrast undercoat, gives a vivid base and realistic shading in a single application. This is the type of paint you'll be thinning; its one-coat shading effect is exactly what you want to preserve, so use Contrast Medium to thin it.
  • Warhammer Colour: Layer- Canoptek Alloy: Warhammer Colour: Layer- Canoptek Alloy is a high-quality acrylic paint designed to be used straight over Base paints without mixing. Layer paints are not Contrast; they can be thinned with water, but don't confuse them with Contrast paints when following this guide.
  • Citadel Air: Vulkan Green: Citadel Air: Vulkan Green is a high-quality acrylic paint specially formulated to work with your airbrush, matching existing Citadel colors and giving a smooth matt finish. If you want to spray Contrast-like effects, use Air paints instead of thinning Contrast for an airbrush; they are ready to spray.