Free Blown Glass is one of the oldest methods for making glass. A worker using a blowpipe (aka pontil or punty) shaped the glass with tongs and shears. The molten glass was held by the pontil rod while the glass was still hot. When the rod was broken off, it left a sear or pontil mark on the bottom of the piece. Sometimes a rough pontil mark was polished off.
Mold Blown Glass was a popular and widely used technique during the nineteenth century. With this method, the glass was blown into a small mold (either wood or iron). The mold gave the piece a pattern. when it was removed. The worker continued to blow and rotate the glass until it reached the desired size and shape. Handles, feet, and other added portions were usually hand-blown and were attached after the fact. The patterns were typically swirls, ribbing, or quilting and they appeared to be inside the glass. This glassware has an almost polished appearance.
Mold-Pressed Glass by mechanical means is dated around the 1820s. It was made by shaping an object via a gather of molten glass placed into a mold and pressed with a metal plunger. This was basically a two man operation: a gatherer and a presser. Between 1827-1840 pieces were normally pressed one piece at a time. Since hand finishing was not a part of the pressing process, the edges of rims and bases were rough. The pressing process became the standard method of making the majority of American glassware by the late 1850s. The presses were hand operated until 1864 when a steam press was patented. The mold pressed method of making glass was economically stimulating and a great technological advancement for the glassmaking industry. Its importance is ranked next to the discovery of glassblowing. The mechanical presses allowed tremendous pattern diversification and skilled workers could be replaced with cheap, unskilled labor. This made a greater variety of glassware available to the public at lower prices. Mold Pressed glassware attained its greatest popularity between 1850 and 1900.
Pressed Glass Methods. Pressed glass is made is made by pouring molten glass into a mold to form the outer surface of an article. A plunger is lowered and forms an article with a smooth interior and a patterned exterior. There are three different methods: Block Molding - one piece mold is used for this method; Split Molding - two or more molds are used; and Font Molding - all articles pressed are identical in form and dimension. Fine pressed pieces were often finished by hand to remove mold marks and could be difficult to distinguish from cut glass.