Glass: A Pocket Dictionary Of Terms Commonly Used - Corning ...

68
Post: The glass used to attach a second pontil to glass
that is about to be pulled into a cane.
Post technique: instead of being applied to a vessel
with a wad, the pontil is attached to a flat plate of glass
called a “post,” which is then affixed to the base or footring
of the vessel.
Pot: A fire-clay container in which batch is fused and
kept molten. The glassworker gathers glass directly
from the pot.
Potash: Potassium carbonate. it is an alternative to soda
as a source of alkali in the manufacture of glass.
Potash- or Potassium-lime glass: A form of glass containing
three major compounds in varying proportions:
silica (usually about 60–75 percent), potash (12–18 percent),
and lime (5–12 percent). Forest glass is a common
type of potassium-lime glass. Potash glass is slightly
denser than soda-lime glass; it passes from the molten
to the rigid state more quickly, and it is therefore more
difficult to manipulate into elaborate forms. However,
it is harder and more brilliant, and it lends itself to decorative
techniques such as facet cutting and copperwheel
engraving.
Preserving jar: A jar for preserving food. The term refers
to jars with a variety of methods for sealing the contents.
John landis Mason perfected the first inexpensive method
of sealing glass jars in 1858.
Pressed glass: Glassware formed by placing a blob
of molten glass in a metal mold and pressing it with
a metal plunger or “follower” to form the inside shape.
The resultant piece, termed “mold-pressed,” has an
interior form independent of the exterior, in contrast
to mold-blown glass, whose interior corresponds to
the outer form. The process of pressing glass was first