Technique

Thinning Miniature Paints: General Guidance

Thinning is adding something to paint so it flows and covers the way you want. The right thinner and the right amount depend on the paint, so treat the notes below as general principles and follow the manufacturer's instructions for the specific product.

Why thin at all

Thinner paint flows into detail, dries flatter, and lets you build color in layers instead of one thick coat. Thick paint can obscure fine detail and dry with visible brush marks. The aim is usually several thin, controlled coats rather than one heavy one.

Water-based acrylics

For water-based acrylics, painters commonly thin with water or with a manufacturer's medium or flow improver. Water alone lowers the binder concentration as well as the viscosity, so very watery mixes can dry to a weaker, more easily disturbed layer, while a medium usually keeps more of the film's integrity. Either way, add thinner a little at a time.

  • Add thinner to paint in small increments and stir; it is hard to un-thin a mix.
  • Different colors in the same range often need different amounts, since some are already more fluid.
  • A manufacturer medium is designed to be mixed with that range; water is a general-purpose option.

Airbrush use

Airbrushing needs thinner paint and often a dedicated airbrush thinner or flow improver to avoid tip-dry and clogging. Airbrush products and regular brush paints are not always interchangeable even within one brand. Follow the manufacturer's recommended ratios for the product and your nozzle, and do not thin an airbrush product with a medium the maker does not list as compatible.

When the paint is not water-based

Enamels, lacquers and alcohol-based acrylics are thinned with the solvent the manufacturer specifies, never with water. Using the wrong solvent can ruin the paint or produce a lumpy, unworkable mix. These products also carry the manufacturer's handling, ventilation and disposal instructions, which should be read and followed.

Common pitfalls

Over-thinning so the paint no longer covers, letting paint dry on the brush or airbrush, and mixing incompatible products are the usual problems. When in doubt, use a dedicated medium from the same range as the paint, and check the manufacturer's guidance before mixing products from different makes.