Manufacturing process

It is difficult to be able to properly identify Georgian glasses without understanding how those glasses were made.  By understanding the manufacturing process you can identify features in glass that would not have been possible in the eighteenth century,  This page attempts to provide an outline of how most drinking glasses were made throughout the Georgian period.

Georgian drinking glasses were blown or blown moulded.  That is to say that a blowing iron, similar to a blow pipe except in material, was used to create the hollow part of the vessel.   A gather of glass was obtained by dipping the blowing iron in the pot of molten glass.  The nearer the middle of the pot, the better the quality of glass (the glass contained more impurities towards the edge and this lesser glass was called tale glass).  Dependent on the object being blown, one or more gathers might be taken by the servitor or gatherer, one of a team of typically four men who would work on the same glass. 

The gather was then rolled on the marver, a polished work surface, and air was then blown down the blowing-iron to inflate the gather to the correct size.  This inflated gather would become the eventual bowl of the drinking glass.   Gathering the correct amount of molten glass to make a specific model was important as this would partially dictate the thickness of the bowl. 

In order to make the stem another gather of glass was picked up and attached to what would become the base of the bowl.  In the event that a preformed stem, such as an opaque twist stem, was to be used then this would be attached to the base of the bowl using a small amount of molten glass.   The gaffer or glassmaker, the leader of the team, or chair as it was called, would manipulate the glass using a number of fairly basic tools.  He had measuring tools including callipers for measuring thicknesses, iron compasses for measuring diameters, and a graduated measuring stick for measuring height.  He had a number of shears for cutting bowl rims or stems to size, and he had a number of pincer-like tools to manipulate the glass.  The most important of these tools, at least in terms of the amount of use they got, were the pucellas, which were similar to pincers but with a spring to them.

Once the stem had been attached to the bowl it was the turn of the foot.  The foot was blown in the same way as the bowl by the footmaker, the third member of the team, and attached to the end of the stem using a small amount of molten glass.   The bubble would then be broken and the foot shaped, either leaving an inward fold to make a folded foot or leveled out to make a conical foot.

Up until this time very little attention had been given to the bowl of the glass as the bubble of glass that would become the bowl was still attached to the blowing-iron. 

Once the foot was completed, a pontil rod of iron was introduced.  A small gather of molten glass was picked up on the tip of the pontil rod which was then attached to the middle of the base of the foot using the gather to attach one to the other.   The blowing-iron was then cracked off the bowl and the pucellas used by the gaffer to shape the bowl to the required design.  The gaffer typically did all the complex work from a chair, and hence the name given to the team, the other three working around him.  The gaffer's job was a difficult one as he had to balance the workability of the glass with all his other responsibilities.  Too cold and the glass became unworkable, too hot and the glass became too fluid.  Occasional trips back to the furnace had to be made to reheat the glass to the optimal temperature.  This reheating process was carried out by inserting the glass into a Glory Hole, a small recess into the furnace where the glass could be heated up without exposing the workman to the full heat of the furnace.

Once the gaffer had shaped the bowl to the required specifications and had measured it up for cutting using compasses with chalk at one end to mark the hot glass, the bowl was cut or sheared.  Because the shearing action left edges to the glass that would make drinking from it an unpleasant experience the glass would be returned to the Glory Hole to refire the rim, producing a soft, rounded edge.

This now left the finished glass attached to the pontil rod which was broken off by sawing a slight nick into the join and dribbling cold water on to the crack.  A sharp knock on the rod would then break it off from the glass which would then be taken by the last member of the team, the taker-in, to the annealing process which would toughen the glass up during the cooling process.  The taker-in was normally a youth, often no more than ten years of age, who also performed all sorts of menial tasks for the other three in the chair.

So what does this manufacturing process tell us about identifying a Georgian glass? 

The following points must be true of any Georgian glass:

  • every glass was made in two or three pieces, never one.  The foot was always made separately and attached to the stem which may have been extruded from the same piece of glass as the bowl, or which may have also been a separate component.  The glass for the foot was taken from the same pot as the glass for the bowl so the colour and clarity should always be the same.
  • every glass must have a pontil scar.  Until the very late eighteenth century the rough mark in the middle of the base of the foot left by the pontil rod being broken off was left rough.  A polished pontil mark denotes a later glass.  No pontil mark denotes a relatively modern glass.
  • both the bowl and the foot of the glass will show striations, circular marks where the glass was worked and teased outwards using the pucellas.  The bowl will also show vertical toolmarks made by the pucellas drawing it out.  These will appear as faint lines running from the rim of the bowl down the sides.  Holding a Georgian glass up against natural light will show both striations and vertical tool marks.
  • the rim of the bowl will be very slightly thicker than the rest of the bowl and will have a soft convex curve to it, all caused by refiring the rim of the glass after shearing.  It may also have a tiny ridge somewhere on the edge where the shears ended the cutting.

There are a small number of glass artists making Georgian-style glasses using the same methods even today.  The characteristics above do not ensure that the glass is eighteenth century.  Their absence means that they are almost certainly not.

 

 

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