Scale model lumber is usually weathered after the model structure has been built and painted, using stain painting, washing, drybrushing and similar weathering techniques to achieve realistic results. These painting techniques are routinely used on simulated wood surfaces of plastic model kits to reduce the unrealistic colour saturation and sheen of plastic parts. The Kibri Old West building pictured here has been treated in this way.
Models built from scale lumber will appear even more realistically weathered if the wooden parts are naturally discoloured and bleached by ultraviolet light. The wire mesh basket above is used to expose scratchbuilt 1:72 scale palisade stakes to sunlight. The picture below shows the same palisade stakes after four months of exposure to the sun, wind, and rain.
This scale lumber will be used in a diorama of the Limes Germanicus once it has been bleached to a natural grey like that seen in the example below.
One disadvantage of weathering scale lumber by sunlight is that the bleaching and discolouration only effects the very surface of the wooden parts, and any cracks or scratches will reveal the fresh wood colour underneath. Retouching such damage with paint or wood stain can be difficult, because the naturally bleached colour will be difficult to match; additional exposure to the elements is not an option either, since the completed model is sure to be destroyed in the process. Sunbleached scale model lumber cannot be cut, carved, or sanded without damaging the weathered surface. Accordingly, all parts need to be cut to fit prior to weathering.
Stained finishes are a quick and easy alternative to natural weathering by ultraviolet light. Scale model lumber treated with grey wood stain or grey artist's oil colours thinned with citrus turpentine looks quite realistic, and the stain may be used to retouch any cuts and scratches. Keep the wood stain in a clear jar and dip or immerse any scale model parts which need to be treated. Place the stained parts on bubble wrap, to allow excess liquid to drain away, and to prevent the wooden parts from sticking to eachother or the work surface.