Model Paint Thinning Ratios
Thinning model paint correctly is one of the most important skills in scale modelling. Too thick and you lose detail; too thin and coverage suffers. Different paint brands require different thinners and ratios. This reference covers the most popular model paint ranges available in the UK.
Thinning Ratios by Brand
Ratios are expressed as paint : thinner. For example, 1:1 means equal parts paint and thinner. These are starting points — adjust based on paint age, colour (whites and yellows often need different ratios), and personal preference.
| Brand / Range | Type | Brush ratio | Airbrush ratio | Recommended thinner | Pot life (thinned) |
|---|---|---|---|---|---|
| Tamiya Acrylic (X/XF) | Acrylic (alcohol) | Neat or 3:1 | 1:1 to 1:2 | Tamiya X-20A or isopropyl alcohol | 4–6 hours |
| Tamiya Lacquer (LP) | Lacquer | Not recommended | 1:1 to 1:1.5 | Tamiya Lacquer Thinner | 2–4 hours |
| Vallejo Model Color | Water-based acrylic | Neat or add drops of water | 1:1 with Vallejo Airbrush Thinner | Vallejo Thinner or distilled water | 8+ hours |
| Vallejo Model Air | Water-based acrylic | Not ideal (very thin) | Neat or add 10–20% thinner | Vallejo Airbrush Thinner or Flow Improver | 8+ hours |
| Citadel (Games Workshop) | Water-based acrylic | Neat or thin with water (2:1) | 1:1 with Lahmian Medium or water | Water, Lahmian Medium, or Vallejo Thinner | 8+ hours |
| Humbrol Enamel | Enamel | Neat or 4:1 | 2:1 to 1:1 | Humbrol Enamel Thinners | 6–12 hours |
| Humbrol Acrylic | Water-based acrylic | Neat or add drops of water | 1:1 with water or acrylic thinner | Water or Humbrol Acrylic Thinner | 8+ hours |
| Mr Color (Gunze) | Lacquer | Not recommended | 1:1.5 to 1:2 | Mr Color Levelling Thinner | 2–4 hours |
| AK Interactive 3rd Gen | Water-based acrylic | Neat or 3:1 | 1:1 with AK Thinner | AK Interactive Thinner or distilled water | 8+ hours |
| Revell Aqua Color | Water-based acrylic | Neat or 3:1 | 1:1 with Revell Aqua Thinner | Revell Aqua Color Mix or distilled water | 8+ hours |
| Revell Enamel | Enamel | Neat or 4:1 | 2:1 to 1:1 | Revell Enamel Thinner | 6–12 hours |
Pot life refers to how long the thinned paint remains usable in the airbrush cup or palette. Lacquer paints dry fastest; water-based acrylics can be kept workable longer with retarder.
Airbrush Consistency Guide
The ideal airbrush consistency is often described as "skimmed milk" — the paint should flow freely when swirled in the cup but still have visible colour. If the paint beads or pools on the surface, it is too thin; if it spatters or clogs the needle, it is too thick.
Paint & Finishing Calculators
Use our free tools for paint mixing and coverage:
- Paint Mixing Calculator — calculate exact paint and thinner volumes
- Paint Coverage Calculator — estimate how much paint you need for a model
Ratios are guidelines and will vary with paint age, colour, ambient temperature and humidity. Always use adequate ventilation when working with lacquer and enamel thinners. Water-based acrylics are the safest option for enclosed spaces.