Method for fusion drawing ion-exchangeable glass

A method of making glass through a glass ribbon forming process in which a glass ribbon is drawn from a root point to an exit point is provided. The method comprises the steps of: (I) cooling the glass ribbon at a first cooling rate from an initial temperature to a process start temperature, the initial temperature corresponding to a temperature at the root point; (II) cooling the glass ribbon at a second cooling rate from the process start temperature to a process end temperature; and (III) cooling the glass ribbon at a third cooling rate from the process end temperature to an exit temperature, the exit temperature corresponding to a temperature at the exit point, wherein an average of the second cooling rate is lower than an average of the first cooling rate and an average of the third cooling rate.