A good airbrushing paint job on a scale model will give it a brand new look. But hobbyists striving for realism will often want to give the model a weathered, worn look. The essence of weathering a scale model lies in making the model look the way it would after going through the wear and tear of real life. Age, litter, dust and dirt, grease, exhaust stains, fading, rust and all the after effects of the environment have to be replicated in the model. A helpful guide is to look at a detailed photograph of the real thing, whether it is a car, plane, ship, train or building, and see how the same effects can be created on the scale model.

In creating a weathered look on the scale model, the airbrush becomes an invaluable tool. A Gravity Feed  Double-Action internal mix airbrush is recommended. Creating wear and tear effects on a scale model is highly detailed work and only an airbrush with these specifications will give the hobbyist the control to achieve these. It is important to remember that the paint used to create a weathered look is just like the paint used to create a brand-new look. It requires the same care, attention and protection. The paint to use in weathering is a matter of choice. Acrylics are recommended because they resist chemicals in thinners, do not lift the paint and last long. They also dry faster compared with oil-based paints.

The common techniques used in weathering a scale model are pastel chalks, washes, highlighting, dry brushing, airbrush hazing and fading. To start, a smooth coat of primer should be airbrushed on the model, especially if a lacquer-based paint like oils or enamels is used.

With washes, brushing mineral spirits over the whole model will break up surface tension. Then a mix of mineral spirits with oil paint is brushed it over the model, letting it drip into the nooks and crannies. There are specially prepared water-based washes available in the market for this purpose.

In highlighting, a light layer of the base color is airbrushed on the spots where the sun would normally hit the object. Artists' oils lighter than the base color is whisked on the model using a paint brush to build up the highlights.

An alternative to the weathering effect of the airbrush is pastel chalks. Soft pastels should be ground on sandpaper, then brushed over the model to simulate dust. The excess chalk is blown away. To preserve the chalk that remains a clear matte finish is applied.

To create a paint chipping effect, silver paint mixed with burnt umber is stippled on edges and corners with a dry brush. Then, a clear flat lacquer is airbrushed to protect the effect. When weathering metallic finishes, which are very delicate,  always make sure to coat the model with an acrylic varnish.