GB/T 12660-2008 "Pulp—Determination of drainability—'Canadian Standard' freeness method" specifies the method for determining the drainability of pulp using the "Canadian Standard" freeness method. It is applicable to various types of unbleached, bleached chemical pulps, and mechanical pulps. By measuring the volume of filtrate after a pulp suspension is filtered for a specific time in a designated instrument, the freeness value is determined, reflecting the drainage rate of pulp fibers. The standard defines instrument parameters, sample concentration, test temperature, and operational procedures, providing critical data for pulp processing and paper quality control in the papermaking process.