Furnace Project 2014

The Ennion jug

The Furnace Project 2014 was devoted to mould-blown glass.
The project led to the creation of copies of the Ennion jug that faithfully reproduce the original. The jug in question is named after an ancient Roman glass-blower who immortalised his name in the vessels he made.
His mould-blown jugs are the most complex design produced in the 1st century AD.


The steps in the process

To make an Ennion jug, a glassmaker needed two ceramic moulds with incised decorations on the inside. These decorations would later be transferred onto the glass when it was blown into the mould (Image 1).

Using a long metal tube known as a blowpipe, the glass-blower removed a large amount of glass from the furnace, which was heated to 1,050 °C. He then made an intentional breaking point in the glass where it was attached to the pipe.
Later he would be able to break the glass vessel off at this point without any risk.

The mould for the body surrounded the soft glass, which the glassmaker inflated by applying his mouth to the pipe and blowing. The glass thereby assumed the correct shape and took on the decoration (Image 2).
The glass-blower repeated this process with the other mould for the base, joined the two parts together while they were still hot and “sticky”, and detached them from one of the pipes at the break point.

Reheating the glass made it mouldable again, thereby allowing the glassmaker to work the neck and rim (Image 3).
The next step was to attach the handle (Image 4).

An annealing furnace kept the vessel warm at a temperature of 450–500 °C for the rest of the day and allowed it to cool overnight.
Without this slow cooling process at relatively high temperatures, cracks would form in the glass, destroying the vessel.

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