Enamel Product.
The perfect color to apply on tank tracks, however it can used to do any type of rusting metal effects. The basic technique used to weather any type of model is the wash, a classic technique that is still one of the most used techniques in modelling today. Apply the washes after shaking the bottle with a large brush to pick out details and creating shadows.
The excess of the wash can be easily removed with a clean brush and White Spirit.