Abstract: A parts cleaning tank and aluminum parts basket had been built by a first shift press operator. The tank and basket were designed to enable the fab shop press operators to clean their tools on location, rather than in the tool crib. At approximately 10:00 a.m. on September 20, 1988, a first shift press operator was instructed to take the tank to the chemical room and fill it with solvent. A stock room attendant unlocked the chemical room, the press operator asked for the parts cleaning solvent, and the attendant pointed out a drum and told him to use it. After he put 3 to 4 gallons of liquid and the aluminum basket into the tank, it was rolled back to the press area and positioned there. At approximately 10:00 p.m., on the second shift, an operator noticed a bluish tint to the liquid, but didn't report it. Later during the third shift on September 21, employees in the area began to notice a whitish haze in the building and could smell and/or taste battery acid. Between 4:00 and 5:00 a.m., someone noticed that the liquid in the tank was boiling and producing a lot of fumes. The tank was moved outside by a forklift truck and the Fire Department was called. Employees #1 through #7, from the third shift, were hospitalized because of breathing difficulties, chest pains, and dry throats. They were kept in the hospital for 8 to 10 hours, given oxygen, then released. The employees did not work the third shift that day, but returned to work on September 22, 1988. The liquid in the drum that was used was not a safety solvent, but Hydrite S133, which contains methylene chloride and 1,1,1-tricloroethane. A sign above the drum was marked "safety solvent."