Atterberg Limits describe the water contents at which clays change behavior. The water content indicating the division between the liquid and plastic state is the liquid limit. The Liquid Limit is determined using a brass liquid limit device cup. The clay is sieved to #40. The clay is added to the cup. A groove of standard depth is made. The brass cup is subjected to a series of small drops that are counted. The groove slowly closes with each blow. The liquid limit is detremined when the groove closes 1 in. at 25 blows.