Sludge wash basics

A "sludge" wash is a useful technique for weathering wheels and tyres, imparting the effect of dust and dirt that settles in recessed areas. For this we'll need Humbrol Weathering Power and something to mix it it, in this instance a plastic shot glass from a poundshop.

Using an old brush, mix some of the weathering powder and some water together, the consitency will determined the final effect - a more runny mix will result in a less weathered finish.

Apply the mix to the wheel, depending on the effect you are after you can either cover the tyres only or the hub as well.

Don't panic, it's supposed to look like this! With the sludge mix in place allow it to dry for around half an hour.

The next stage is to removed the sludge mix with a dry, firm brush. The Humbrol Stipple Brushes (AG4303) are ideal for this.

Use a scrubbing motion and start to remove the sludge mix. 

After a few minutes the sludge mix will start to wear away revealing the painted tyre underneath. Keep scrubbing awa, making sure the brush remains dry,

For more heavier wear, a piece of Scotchrbite or any similar material (on old kitchen scourer) can be used to scrub the mix away from the tread areas.

A before-and-after shows how a simple technique can produce realistic results. Further weather effects like washes around the hub will create more depth and simulate grease and oil stains.