Miniature Painting
How to Thin Acrylic Paint for Miniatures
Thin miniature paint to roughly the consistency of whole milk: put a drop of paint on your palette, add water a half-drop at a time (start around 1 part water to 2 parts paint), and mix until the paint flows off the brush smoothly but doesn't run into recesses on its own. Two thin coats beat one thick one on every miniature ever painted. Here's how to judge it, when to use mediums instead of water, and the signs you've gone too far.
Why "two thin coats" is the oldest advice in the hobby
Paint straight from most pots is formulated for coverage, not for 28 mm sculpts. Used neat, it behaves like house paint: it fills the mail links, softens the fur texture, and leaves visible ridges at every brushstroke edge. The sculptor put detail on that mini at fractions of a millimeter. Thick paint is how you sand it off with a brush.
Thinned paint settles into a level film and lets the sculpt show through. The trade is opacity, which is why coat two exists. Coat one looks streaky and wrong. Don't panic; that's the process working. Coat two, applied after the first fully dries, reads as solid color.
The milk test (and two others)
Nobody measures thinning in a lab. You calibrate by feel, using checks like these:
- Whole milk. Basecoat consistency. The mixed paint should sheet off a tilted palette like milk, not crawl like syrup or race like water.
- The palette streak. Drag your loaded brush across the palette. A smooth opaque line with soft edges is right. Ridges at the stroke edges mean too thick; a transparent watery line with dark edges means too thin.
- The drag test on the model: if the brush skips or the paint ropes behind it, add water. If the paint runs off the raised area and pools in the recess below, you've overshot.
Different jobs want different mixes, which trips people up. Basecoats sit around milk. Layering and glazing go much thinner, edge highlights slightly thicker so the line holds. When someone's minis look chalky and rough, the answer is almost always "thin your paints." When their colors won't cover anything after four coats, the answer is "stop thinning so much." Both painters think consistency is a fixed setting. It's a dial.
Water or medium?
Plain tap water handles most thinning, and it's the right default. Water has one failure mode: past roughly 1:1, it starts breaking the acrylic binder apart, and the paint dries patchy and fragile with pigment separating at the edges.
That's what acrylic mediums are for. A drop of matte medium or brand-name "thinner" dilutes the paint while replacing the binder, so you can go very thin (for glazes especially) without the paint falling apart. Flow improver is a different tool: a wetting agent that reduces surface tension so paint releases from the brush more easily, useful in tiny quantities and easy to overdo.
Starting kit reality check: water plus patience covers your first fifty minis. Buy a bottle of medium when you start glazing, not before. (Your money goes further on a decent brush first.)
Speedpaints: mostly don't
Speedpaints and contrast paints come pre-thinned to their working consistency; that's the product. Use them straight from the bottle for normal work. Adding water weakens the shading effect, and adding much water makes them dry patchy.
The exception is deliberate: each brand sells a dedicated medium (Contrast Medium, Speedpaint Medium) for turning a strong color into a subtle tint. Thinning speedpaint with its medium is a real technique. Thinning it with water is usually a mistake. More on how these paints behave in our speedpaint vs. traditional comparison.
A wet palette changes the math
Paint on a dry palette starts thickening within a couple of minutes as water evaporates, so the mix you calibrated drifts thicker while you work. A wet palette (parchment over a damp sponge) feeds moisture up into the paint and holds your mix at the consistency you set, for hours. It's a $15 purchase or a DIY sandwich-box project, and it's the reason experienced painters seem to fuss with their paint less than you do. They calibrated once.
Frequently asked questions
What consistency should miniature paint be?
About whole milk for basecoats: flows smoothly off the brush, covers in two coats, doesn't run into recesses on its own. Glazes go far thinner, washes come pre-thinned, and edge highlights run a touch thicker so the line stays put.
How many drops of water per drop of paint?
Start around one drop of water to two drops of paint and adjust by feel; brands vary a lot out of the pot. Past one-to-one, switch from water to an acrylic medium so the binder doesn't break down.
Do you need to thin Citadel or Vallejo paints?
Almost all of them, for basecoating. Vallejo Model Color and Citadel Base paints come dense and want a real dilution; layer-type paints need less. The exceptions are washes and speedpaint-style products, which are sold at working consistency.
Why does my paint look chalky or streaky?
Chalky usually means the paint dried too fast or was overworked as it dried; streaky means too thick or brushed over a half-dry coat. Thin properly, lay a stroke, and leave it alone until it's fully dry before the second pass.
Can I use flow improver instead of water?
Use it with water, not instead. A single drop in your rinse water or mix reduces surface tension and helps paint release smoothly. On its own it doesn't thin much, and too much makes paint crawl and bead on the model.