In North Carolina one hundred or more years ago, long-leaf pine trees were closely tied to the turpentine industry and products such as the Original Vicks Vapo-Rub, household cleaners, medicines for burns, bites, and stings, and pitch used to help keep wooden ships from sinking. Cat-faced notches were cut into pine trees so resin would run downward into a container, and Dr. Charles Herty developed an efficient cup for collecting pine resin at the base of the tree. The resins were distilled in large vats and turned into a thick substance called pitch, which was packed into wooden barrels for shipment and used for naval waterproofing. The industry was labor-intensive and was usually worked by convicts leased from law enforcement agencies and or low-wage employees paid in company script redeemable only at company stores, where debt often kept workers tied to the company until their debts were paid. In the late 1800s, after pine forests in other Southeastern states were played out, the turpentine industry shifted south to Florida. By the mid-1900s, the industry had largely faded because turpentine was identified as a carcinogen, ships were made of steel rather than wood, and synthetic materials had emerged.