A glass container is provided that includes a tube, a circular bottom, and a longitudinal axis. A curved glass heel extends from an outer end the bottom to the first end of the tube. The two-dimensional distance h(x,y) between a contact plane and the outer surface. The two-dimensional distance is measured in a direction parallel to the axis. The slope magnitude of the outer surface at the given position x,y is given by
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}.
The 75% quantile of values that have been determined for the term
√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta
for all given positions x,y within a circular area having a radius of 0.4×d2/2 and that correspond to the centre is less than 4100 μm/mm. The adjacent positions x,y increase stepwise by 200 μm, and h(x,y).sub.delta=h(x,y).sub.max−h(x,y).sub.min, h(x,y).sub.max is a maximum value for h(x,y) and h(x,y).sub.min is a minimum value for h(x,y) being determined in that circular area.

A glass container is provided that includes a tube, a circular bottom, and a longitudinal axis. A curved glass heel extends from an outer end the bottom to the first end of the tube. The two-dimensional distance h(x,y) between a contact plane and the outer surface. The two-dimensional distance is measured in a direction parallel to the axis. The slope magnitude of the outer surface at the given position x,y is given by

√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}.

The 75% quantile of values that have been determined for the term

√{square root over ((dh/dx).sup.2+(dh/dy).sup.2)}×d1/h(xy).sub.delta

for all given positions x,y within a circular area having a radius of 0.4×d2/2 and that correspond to the centre is less than 4100 μm/mm. The adjacent positions x,y increase stepwise by 200 μm, and h(x,y).sub.delta=h(x,y).sub.max−h(x,y).sub.min, h(x,y).sub.max is a maximum value for h(x,y) and h(x,y).sub.min is a minimum value for h(x,y) being determined in that circular area.

A glass container is provided that includes a tube, a circular bottom, and a longitudinal axis. A curved glass heel extends from an outer end the bottom to the first end of the tube. The outer surface has a topography defined by a function ĥ(x) that is an azimuthal average of a distance between a contact plane and the outer surface at any given position located on a circle having the centre and the radius |x|. The values ĥ for ĥ(x) are determined for a plurality of circles the radius of which increases stepwise by 500 μm starting with a circle around the centre having a radius of 500 μm. The values ĥ are determined in a range from x=−0.4×d2/2 to x=+0.4×d2/2, d2 having a size such that at least 4 values ĥ are determined and can be fitted with a curvature function

[00001]$\hat{h}\left(x\right)=\frac{-c\times x^2}{1+\sqrt{1-c^2\times x^2}}+h_0.$

A process for preparing a glass container that includes: providing a glass tube with a first portion, a second portion, and a longitudinal axis (L.sub.tube); holding the first portion in a first clamping chuck and the second portion in a second clamping chuck; rotating the glass tube around the longitudinal axis (L.sub.tube); heating, via a heater, the glass tube above a glass transition temperature; separating the first and second portions from one another by pulling apart along the longitudinal axis (L.sub.tube) while the heated glass tube is still rotating by moving the first and the second chucks away from each other; and moving the heater, while moving the first and second chucks away from each other, so that the heater follows a mass that remains at a circular end region of the first and/or second portion.

A method for thermally treating an annular region of an inner surface of a glass container produced from a borosilicate glass tube is provided. The annular region is disposed at a tubular portion of the glass container and is disposed adjacent to a glass container bottom. The method includes: forming the glass container bottom from the glass tube; heating the annular region of the inner surface of the tubular portion to a treatment temperature T.sub.Beh above the transformation temperature T.sub.G, wherein the annular region is adjacent to the glass container bottom; maintaining the treatment temperature T.sub.Beh for a certain time period; and cooling the glass container to room temperature.

A method for thermally treating an annular region of an inner surface of a glass container produced from a borosilicate glass tube is provided. The annular region is disposed at a tubular portion of the glass container and is disposed adjacent to a glass container bottom. The method includes: forming the glass container bottom from the glass tube; heating the annular region of the inner surface of the tubular portion to a treatment temperature T.sub.Beh above the transformation temperature T.sub.G, wherein the annular region is adjacent to the glass container bottom; maintaining the treatment temperature T.sub.Beh for a certain time period; and cooling the glass container to room temperature.

A method of producing a glass vessel includes holding a borosilicate glass tube with a first holding device, and holding an open end portion of the glass tube with a second holding device such that the second holding device is spaced apart from the first holding device. Heat is applied to the glass tube by a burner to separate the open end portion and form a bottom portion on the open end portion. Fire-blast treatment of an inner surface of the open end portion with a flame from a point burner is performed during at least a part of (i) applying heat to the borosilicate glass tube for separation, (ii) applying heat to the separated open end portion for bottom portion formation, and/or (iii) a period applying heat to the separated open end portion and prior to releasing the glass vessel from the second holding device.

A method of producing a glass vessel includes holding a borosilicate glass tube with a first holding device, and holding an open end portion of the glass tube with a second holding device such that the second holding device is spaced apart from the first holding device. Heat is applied to the glass tube by a burner to separate the open end portion and form a bottom portion on the open end portion. Fire-blast treatment of an inner surface of the open end portion with a flame from a point burner is performed during at least a part of (i) applying heat to the borosilicate glass tube for separation, (ii) applying heat to the separated open end portion for bottom portion formation, and/or (iii) a period applying heat to the separated open end portion and prior to releasing the glass vessel from the second holding device.

An improved method and an improved apparatus are provided for producing a thin glass ribbon, which provide borders at the edges of the ribbon. The edges formed are of high mechanical quality and a formation of new secondary borders after the severing or at least the thickness of such secondary borders is reduced compared to the original borders. The method includes drawing the thin glass ribbon from a molten glass or from a preform, severing the borders, and cooling the resulting glass ribbon. The severing is effected at a location along the moving direction of the thin glass ribbon and at a time at which during the cooling of the thin glass ribbon the viscosity of the glass is in a range from 10.sup.7 dPa.Math.s to 10.sup.11 dPa.Math.s, so that the edges of the thin glass ribbon newly produced by the severing of the borders are rounded off.

An improved method and an improved apparatus are provided for producing a thin glass ribbon, which provide borders at the edges of the ribbon. The edges formed are of high mechanical quality and a formation of new secondary borders after the severing or at least the thickness of such secondary borders is reduced compared to the original borders. The method includes drawing the thin glass ribbon from a molten glass or from a preform, severing the borders, and cooling the resulting glass ribbon. The severing is effected at a location along the moving direction of the thin glass ribbon and at a time at which during the cooling of the thin glass ribbon the viscosity of the glass is in a range from 10.sup.7 dPa.Math.s to 10.sup.11 dPa.Math.s, so that the edges of the thin glass ribbon newly produced by the severing of the borders are rounded off.