I can tell you about moulds and pressing at Fenton Art Glass today, and I’m generally familiar with historical materials relating to glass pressing in the USA back to the 1840s. The question relating to moulds used to make Victorian-era pressed glass items is best approached by considering what is known in the glass industry as a “joint mould” (there are other kinds--such as block moulds and shell moulds--but let’s save those for another time). These joint moulds were used on side-lever presses, and the typical procedure would be that only one mould was used; for some pressed items (generally smaller articles) there might be two moulds. A rotary press here at Fenton uses four moulds. We do not have any automatic pressing machinery, but I have heard of such machines that have as many as 28 moulds and produce about 14,000 tumblers per hour when all is going well.
A joint mould for pressing glass has these parts: plunger; mould (typically 2, 3 or 4 parts depending upon the size and shape of the piece and the depth of the pattern); two handles; bottom plate; ring with handle; and key with handle. The key and the ring have to be removed after each pressing operation so than the mould can be opened and the object can be taken out. If anyone needs further clarification of these parts, let me know in this forum. In the meantime, examine some of your pressed glass items and see how many joint marks various items have.
Joint moulds are typically used on a hand-operated side-lever press. The lever is always on the right, so this is a right-handed operation, and a weighted counterbalance makes the job of the presser just a bit easier. At the start of production, the mould is placed on the flat table of the side-lever press, and the mould will slide on the lubricated surface of the table to be properly positioned directly under the plunger. Moulds are quite heavy, and the presser and a helper (called turning out worker) standing to his left work together to move the mould as needed. We have side-lever presses still in operation that are many years old, and none of them has a table that would accommodate more than two moulds. In looking through materials (1890 to present) relating to union-management agreements regarding pressing, I see references to production using two moulds on a side-lever press but I’ve never seen a mention of three or more moulds on a side-lever press. A rotary press (there is a US Patent for such in 1876) typically has four moulds (but just one plunger).
Lastly, I cannot envisage a pressing operation where the piece is somehow pressed more than once. The object cannot be removed from the mould until it has cooled (workers say the glass has “set up”) sufficiently so that it will not deform (called “run down”). You might reheat the piece in a glory hole to do something like crimping or otherwise changing the shape, but I have never heard of making a pressed item smooth and then pressing again to impart pattern.
Topic: How many moulds where used in victorian pressed glass. (Read 965 times)
