Green coffee is sorted/separated to remove visual defects, foreign matter, and to create a more uniform size range of beans. There are several methods used to sort/separate green coffee: hand sorting, density table, color sorting both visual and electronic, and screen size. Electronic color sorting (Automated Optical Sorting) uses a special camera to evaluate the color of a bean compared to a preprogramed color range. If the bean is out of the range, a brief (1-3msec) puff of air removes it from the fast moving stream of beans flowing through the machine. This method can also be done (although not as quickly) with the human eye. Screen sorting runs the coffee through a series of sieves of different sizes, thus separating beans according to size. The holes of the sieves are gauged in .4mm (1/64 in.) increments.