text: This was developed independently by R L Blaine of the American National Bureau of Standards, and uses a small glass kerosene manometer to apply suction to the powder bed.  It differs from the other methods in that, because of uncertainty of the dimensions of the manometer tube, absolute results can't be calculated from the Carman equation.  Instead, the apparatus must be calibrated using a known standard material.  The original standards, supplied by NBS, were certified using the Lea and Nurse method.  Despite this shortcoming, the Blaine method has become by far the most commonly used for cement materials, mainly because of the ease of maintenance of the apparatus and simplicity of the procedure.