What is a KB value?
The kauri-butanol value (KB) of a solvent represents the maximum amount of that solvent that can be added to a stock solution of kauri resin (a fossil copal) in butyl alcohol without causing cloudiness. Since kauri resin is readily soluble in butyl alcohol but not in hydrocarbon solvents, the resin solution will tolerate only a certain amount of dilution. “Stronger” solvents such as toluene can be added in a greater amount (and thus have a higher KB value) than “weaker” solvents like hexane.
