US Patent 7105350 Closure integrity test method for hot-fill bottling operation

A method for evaluating the integrity of the closure on a hot-filled container in which the hot-filled container is subjected to a pressurized spray of cooling medium, including the step of providing a cooling medium having an effective amount of a fluorescing dye contained therein, is provided. The sealed container then is sprayed with the cooling liquid. After the container has exited the cooling portion of the filling and sealing operation, the container is subjected to ultraviolet light to activate any fluorescing dye which may have migrated past the closure into the interior of the container. The container is then viewed to determine the presence or absence of activated dye.