Measurement errors can be expensive.
Time spent using density gradient columns is time wasted if the equipment is not calibrated traceably to recognised national standards. The glass floats in density gradient columns can easily lose their calibration if they are mistreated. They will then provide inaccurate readings which compromise your quality control. To maintain accurate and reliable density measurement you need the highest quality floats available. They must have traceable calibration and be recalibrated from time to time.