Lovibond is 525 degrees +/- 25. Black barley (dark roasted unmalted barley) provides the color and sharp, acrid flavor that is characteristic of stouts and some porters.
It also imparts a characteristic dryness. Black barley (roasted flavors) and black malt (used for color) are not interchangeable. Please compare the two before choosing. Use 3-7% in porters and 5-15% in stouts.