The aim of bed blending is to improve the quality and consistency of the blended material. However, variations sometimes occur in beds, and so monitoring is necessary. Automatic petrographic techniques have been developed to determine the distribution of low-grade filler material within coal layers and major components in blend samples. Uneven distribution of filler was identified as the major cause of variations in the properties of coke produced from coal blends. Consequently, changes were made to bed construction which improved the consistency of the chemical and rheological properties of the blend and the physical properties of the coke.