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Cast Iron Press Molds for glassblowing

The photo below is of a Clevenger Brothers (Clayton, NJ) goblet press mold (with plunger).
This heavy cast iron mold was purchased at auction in New Jersey during the summer of 2009.

Glassblower.Info - Clevenger Brothers - Goblet Press Mold for Glassblowing - Front View
Glassblower.Info - Clevenger Brothers - Goblet Press Mold for Glassblowing - Plunger
The press mold above was intended to be used by one glassblower, making pieces by hand one-at-a-time.

In contrast to a machine like the one below (patented 1903) which has multiple stations (multiple press molds) on a rotary platform:
(J. Schies Glass Blowing Machine Patent 722,634 patented March 10, 1903)
(as found at (Society for Historical Archaeology))

When I toured Fenton in June 2007, you saw the modern version of this rotary press mold still in use.

(you can see four Fenton workers and a mold, the worker in the back is putting three pieces of white glass into the lehr).

In fact, Fenton holds US Patent 7451622 (issued November 18, 2008) - Mold open and close mechanism for an Individual Section (I.S.) machine! So, more than 100 years after the Schies patent, improvements continued...

The background (introduction) of that Fenton patent is as follows:

The present invention relates to I.S. (Individual Section) machines, which produce glass bottles and more particularly to the mold open and close mechanisms for those machines and the molds used in these mechanisms.


An I. S. machine includes a plurality (usually 6, 8, 10 or 12) of identical sections. Each section has a blank station including a mold opening and closing mechanism having a pair of opposed mold arms which is displaceable between mold open and mold closed positions. A mold arm supports a number of inserts on which are placed anywhere from one to four blank mold halves. Each section also has a blow station including a similar mold opening and closing mechanism.

U.S. Pat. No. 5,865,868 illustrates a conventional mold open and close mechanism wherein the mold arms are supported for axial displacement. Mounted on the arm are upper and lower inserts, which will hold one half of each of the required moldspairs. In a triple gob application, an insert may have a first insert portion to support two mold halves and a second insert portion to support one mold half with the first insert portion being mounted relative to the second insert portion to equalizethe clamping forces when the molds are closed.


It is an object of the present invention to provide an improved mold closing mechanism for an I.S. machine and improved molds for use therewith.

Other objects and advantages of the present invention will become apparent from the following portion of this specification and from the accompanying drawings, which illustrate a presently preferred embodiment incorporating the principles of theinvention.

Wheaton has a very informative web page here, from their 1990 catalog.
As with many innovations, this was to increase speed and lower cost, as is described on a small part of that web page:
The United States is credited with the invention of the mechanical pressing of glass into molds in 1825, revolutionizing glassmaking by making possible the mass production of glassware. This new process eliminated the need for an expert glassblower to fashion a piece of glassware. An unskilled laborer could be trained in a few weeks to become a good presser. The technology utilized to produce blow molds was adapted to make press molds.

Pressing, forcing glass into a mold, had been used by ancient Egyptians in the 14th century B.C. to make small figurines. Over three millennia later, glass stoppers and drops for chandeliers were pinched in small hand presses in 18th century Europe and America. A similar tool to these pincers is a hand tool that fashions a walnut-shaped ball which could then be applied as decoration to a vessel.

You can see here that press molds can be 2-part or 3-part molds, and the plungers do not have to be circular in cross-section:

If you are interested in fully-automated glass bottle (glassblowing machines), you can find a fascinating 4-page article here
or on the Society for Historical Archaeology (SHA) website (which has the following photo):


At 12:11:00 September 25 2023 displayed this
glassblowing web page at last modified: November 29 2009