This recommended microscopic practice for evaluating the inclusion content in steel has been developed as a practical method of quantitatively determining the degree of cleanliness of steel. This method has been established as a reasonable control for steel mill operations and acceptance for production manufacturing. It has been widely accepted for carbon and alloy steel bars, billets, and slabs. Exceptions are resulfurized grades which are outside the limits of these photomicrographs and the high carbon bearing quality steels which are generally classified using ASTM E 45-60T, Method A, Jernkontoret Charts.