Donald L Desantis

US Patent:

60949422, Aug 1, 2000

Filed:

Jun 13, 1997

Appl. No.:

8/874529

Inventors:

Charlene A. Falleroni - Lower Burrell PA
Donald L. DeSantis - Hollidaysburg PA
Kevin G. Hill - New Kensington PA

Assignee:

PPG Industries Ohio, Inc. - Cleveland OH

International Classification:

C03B 1300
C03B 1500
C03B 1700
C03B 516

US Classification:

65 992

Abstract:

The present invention provides a method of reducing tin defects in flat glass made by the float process. In the float process, molten glass is delivered onto a pool of molten tin within an enclosed chamber and formed into a glass ribbon. Oxygen gas dissolved in the molten tin combines with the tin to form tin oxide which vaporizes and collects within the chamber, resulting in defects in the glass. In the present invention, hydrogen gas is introduced directly into the molten tin to react with the oxygen gas and tin oxide within the molten tin to form water and elemental tin, resulting in a reduction in the amount of tin oxide within the molten tin. In one particular embodiment of the invention, the hydrogen gas is introduced into the molten tin through an elongated, porous graphite member submerged in the molten tin within the forming chamber such that it extends along and is located outboard of selected portions of the edge of the glass ribbon.