Use of dry sediment works very well for non-cohesive sediment like beach sand and glacial sediments because the particles do not stick to one another and water can be accurately weighed and dry sediment is easy to handle. In other situations, the material must be disaggregated by severe methods such as ultrasonic treatments, grinding, and sieving to reduce brick-like material to powder. Disaggregation, breaking up sediment clumps, makes small particles out of bigger ones, and in the process, causes the sediment to become finer grained than it was in the environment. Consequently, the treatment can give an invalid representation of how OBS sensor will respond in the environment. So when using disaggregated sediment, be aware that the indicated OBS sensitivity can be higher than it would be if the sensor was calibrated by the preferred in situ method. The chart shows how the disaggregation methods influence the turbidity indicated for the sample. Sediments susceptible to disaggregation effects include:

1. organic-rich estuarine mud
2. cohesive and flocculated suspended matter
3. clay-rich sediment