A recycled piece of protective foam strip from a worktop is used while airbrushing the underframe. This helps access to the inside underframe details on the opposite side of the coach to the one I'm painting.

The whole of the underframe will now be treated to a thin coat of Railmatch Sleeper Grime, starting with the bogies. The air flow from the airbrush is used to turn the wheels and paint is then ejected for long enough to coat the whole wheel as it turns.