The Lovibond “52” system for the measurement of color in beer was invented in 1893 by Joseph William Lovibond in Greenwich, England. It involved the visual comparison of standardized colors, in the form of colored glass discs, with samples of beer. This was superseded in 1950 when L.R. Bishop proposed the use of a revised set of slides. Bishop’s revised system was adopted as the EBC standard in 1951 and the standard slides were manufactured by Tintometer Co, UK, as they are to this day.
On the Lovibond scale, a pale golden lager might have a color of 2˚ or 3˚, a pale ale 10˚– 13˚, a brown ale or dark lager 17˚–20˚, all the way through to the near black of imperial stout at 70˚.
Inherent errors in visual color comparison due to the age of the standard slides used, the light used to illuminate the samples, the state of the observer, and various other problems meant that consistency across and within laboratories was difficult to achieve using the Lovibond scale. Although the glass color samples are still available and still used, spectrophotometry has largely replaced Lovibond’s method. The ASBC spectrophotometric method is called the Standard Reference Method (SRM). Though “degrees Lovibond” and “degrees SRM” are very similar, some feel that SRM gives less information about the actual appearance of the color as opposed to its intensity. In Europe, a different scale (an EBC Method) is used, though this scale is also produced using spectrophotometry. Oddly, in the United States, the SRM method is used to refer to beer color, but malt color is designated in degrees Lovibond. At the lower end of the scale, malt color numbers and beer color numbers are related, but as malt becomes darker, the numbers pull away, reaching more than 500˚ for black malts. This reflects the non-linear coloring influence of very dark malts, where it may take a very small percentage of the grist to affect wort color.
Bibliography
Lovibond. Water analysis and colour measurement. http://www.tintometer.com.