treatment with fluorine-containing compounds is typically accomplished through the injection of a fluorinated gas mixture (e.g. 1,1-difluoroethane mixed with air) into bottles at high temperatures. the gas can be delivered to the container either in the air used in the forming process (i.e. during the final blow of the container into its desired shape), or with a nozzle directing a stream of the gas down into the mouth of the bottle as it passes on a conveyor belt after forming but before annealing. the mixture gently combusts inside the bottle, creating an extremely small dose of hydrofluoric acid that reacts with the glass surface and serves to dealkalize it. the resultant surface is virtually free from any residues of the process. this treatment is also known as the ball i.t. process (i.t. standing for internal treatment) as ball corporation held the patent and developed the first commercially available system implementing this process.