A method of producing asphalt strip shingles includes continuously coating a substrate with asphalt to form an asphalt coated sheet, moving the asphalt coated sheet in a machine direction, depositing blend drops of blend drop granules onto the asphalt coated sheet from a blender, providing a signal indicative of the presence of the blend drops at a location downstream from the blender, sensing the color of the blend drops at the downstream location with a sensor, comparing the sensed color of the blend drops with a reference color, and providing a signal indicative of the comparison.