Precleaners will only clean 70% of carryback.  For some sites and some materials, this is good enough. However, some applications have sticky, abrasive materials that can require secondary and tertiary cleaners to produce the best results. In other instances, such as overland conveyors or port facilities, there are environmental standards that must be upheld, and it’s important for carryback to be as minimal as possible.  In these instances, you may need multiple secondary cleaners as well as a wash box. It’s important to keep in mind that carryback isn’t a simple issue. It can lead to belt mistracking, spillage, and rapid component wear (belt, rollers, etc.). It can also lead to a lot of safety issues.