- The research was carried out in ten Seed Analysis Laboratories, located in the State of São Paulo, Brazil. It was used 10 commercial seed lots of guinea grass. The submitted, as well as, the working samples were obtained through a Boerner seed sample divider. It was tested the hyphotesis if the seed blowers were or not responsible for the difference of results between laboratories. The results confirmed the hyphotesis. However, the utilization of calibration sample carried to a homogeneization of the results. It was also showed that seed blowers of same model were operated at different calibrations which carried to a given air pressure at which homogeneous results were obtained.