There are multiple designations for asphalt emulsions. This will teach you everything that you need to know about the designation 'hf' or high float. Everything from use in warmer climate to its use outside of rural roads are discussed.
For instance you can learn about how asphalt emulsions, make liquid asphalt go further by covering more square yardage and aggregate surface area asphalt pavement preservation surfacings than thicker lifts:
While they don’t add structural value, these thin surfacings aren’t intended to. Instead they protect aging asphalt pavements, seal cracks, retain aggregate, waterproof pavement structure, enhance friction, and with rejuvenators, give new life to an aged, oxidized asphalt surface. Emulsions used in full depth reclamation (FDR), though, can add structural value to a pavement cross section.