Which tool should be used for cleaning aggregates sized from #50 to #200?

The correct tool for cleaning aggregates sized from #50 to #200 is the soft china brush. This tool is specifically designed for handling delicate materials without causing damage. The soft bristles of a china brush effectively remove dust, dirt, and other fine particles from the surface of the aggregates, ensuring that the sample retains its integrity and is representative of the material being tested.

Using a soft china brush is ideal in this case because the aggregates in the specified size range are relatively small and can easily be scratched or altered by harsher cleaning tools. The bristles are gentle enough to avoid harming the aggregates while still providing sufficient cleaning capability.

Other tools, such as a soft brass wire brush, steel wool, or a metal wire brush, can be too abrasive and could potentially damage the aggregates, leading to an inaccurate assessment of their properties or quality. Therefore, the soft china brush is the most appropriate choice for this cleaning task.