Looking Back for July 27

50 Years Ago

July 27, 1972

Until 1962, borate was the primary chemical used by the USDA Forest Service as a fire retardant, but borate acted as a harsh soil sterilant of quite long duration and it killed the foliage that it contacted. The Forest Service working in conjunction with the fertilizer industry, developed greatly improved types of fire retardants. The retardants were composed primarily of diammonium phosphate, ammonium sulfate, or liquid ammonium polyphosphate, blended with a coloring agent, spoilage inhibitors and a thickening agent...