"There's a reason coal tar has been made all these years: It works better and asphalt emulsion has some deficiencies." Chris Mariani, vice president of marketing for GemSeal, says the company ...

"A blend is a compromise to a 100% coal tar emulsion," Maclean says. "If you gave any customer the option, for the same price, to a person they would choose 100% coal tar emulsion." Dubey says ...