Patent ID: 7000431

Claim:
A method of preventing schlieren formation in a glass melt flowing through a glass melt feed system ( 20 ) for making products according to the Vello process or the down-draw process, said method comprising the steps of: a) providing a sleeve-type agitator ( 1 ) comprising a cylindrical sleeve ( 6 ), said cylindrical sleeve having a cylinder wall ( 7 ) provided with a pluralty of circumferentially distributed, outwardly protruding vane elements ( 5 ) and openings ( 2 ) in an outer surface of said cylinder wall, said openings ( 2 ) and said vane elements ( 5 ) being formed to at least partly stir said glass melt when said sleeve is rotated; b) arranging said sleeve-type agitator ( 1 ) vertically in a glass melt feed channel ( 3 ′) of said glass melt feed system ( 20 ); and c) rotating said sleeve ( 6 ) provided with vane elements ( 5 ) and said openings ( 2 ) to at least partly stir said glass melt when said glass melt flows downward through said glass melt feed channel ( 3 ′) of said glass melt feed system ( 4 ) and to guarantee exchange of glass material of the glass melt between respective volumes or spaces both inside and outside of the sleeve; whereby schlieren formation in said glass melt and glass material losses are prevented.