The Manufacturing Process

The glowing hole that you can see in this picture is the furnace. Historically, furnaces were fueled with coal, wood and other solid fuels and apprentices would work bellows to achieve the intense heat required to melt the sand lime and potash into glass. Today, we fire our furnace with gas, Glass working temperature is around 1090c (water boils at 100c). The glass that we use is 24% lead crystal. The glass is melted and stored in a crucible inside the furnace. Consequently, the furnace never gets turned off, but remains constantly hot enough to keep the glass liquid inside it. 

Gathering 

The first step in making a piece of glass is the gather. The glass maker takes a preheated steel iron or blow pipe and touches the tip of it into the molten glass. The glassmaker then turns the iron across the surface of the glass until he has the size of `blob' required. The iron now has to be kept in near constant rotation as molten glass has a very syruppy consistency, turning the iron prevents the glass from sliding off it and onto the floor

Shaping

Depending on what sort of piece the glassmaker wishes to make the glass is either marvered, or shaped using a wet wooden block or a wad of wet paper. A marver is a thick sheet of polished steel on which the glass is rolled to shape it. The marver can also be used as a palette to pick up fragments of coloured glass onto the piece. The glass maker above is using a wet wooden block to shape his blob of glass. The `blob' of molten glass is known to Glassmakers as a parison at this stage.

Blowing When the glass maker has shaped the Parison sufficiently he blows down the blow pipe and then holds his thumb over the end of it. the thumb pressure keeps the air in the iron and the heat of the molton glass makes the air quickly expand to create a bubble. This technique is Known as thumbing in. As glass cools it becomes harder and stiffer to work. The glassmaker, therefore, has to reheat the piece during the creation process to maintain it at a workable temperature. he does this by bathing it in heat of another extremely hot chamber which is known as a glory hole. the  photograph shows Master Glassmaker James Adlington, at his glory hole reheating a piece

The Tools

The Glassmakers hand tools are shown below. They are all very simple in design. The tools that are used now are virtually the same as those used 2000 years ago. The wooden tools are made by individual glassmakers for themselves from fruit tree wood, as this is particularly resistant to heat.

Jacks are used to tease hot glass into form. The blocks are used to shape the gather from the furnace into a workable parison. Footboards, as they sound, are used to make the feet of wine glasses and other 'footed' pieces. callipers are set so that glassmakers can monitor the sizes of their bubbles. The interestingly named shears are used for snipping off excess pieces of molton glass.

As the glass makers wooden tools are kept by the bench in a bucket of water this is to prevent them from igniting when they contact with the molton glass

The Pontil

When the piece is ready to be shaped at its unworked end, the glassmakers assistant takes a small gather of glass onto a rod, rolls it on the marver into point and then flattens the end. This is called a pontil. The Assistant then takes the pontil to the bottom of the piece. The Glassmaker then files the piece away from his blowing iron and gives it a sharp tap. The piece then (hopefully) cracks away from the iron he is holding and is caught by the assistant who takes the weight of the piece on the pontil iron that he holds. (photo 8 below) The Assistant then hands the pontil back to the Glassmaker who will reheat the unworked end of the piece and take his toll s to it until it is completed. (photos 9 &10 below) It is always possible to tell if a piece has been handmade by virtue of the mark that the pontil iron leaves on the bottom of the piece. The pontil mark is not an oversight of a defect, but evidence that the piece is a handmade original

The finished piece is tapped from the pontil (photo 11 below) and then placed carefully in a special annealing oven called a lehr. This is so the glass can be `baked' at the same temperature. The glass is left in the Lehr to cool overnight. As pictures are worth thousands of words, the following series of photos shows the various stages in the manufacture of a simple ale house rummer, - from molten blob to classic drinking vessel. 

The photograph here shows a set of the finished rummers. It is only the skill of the glassmaker ensures that the glasses are an evenly matched set.



The Making of an Ale House Rummer

1. Gather at furnace		2.Blocking the gather		3.Blowing a bubble
4.Adding stem		5.Shapping stem with jacks		6.Adding foot
7.Shaping foot		8.Adding pontil		9.Heating at glory
	10.Opening the bowl		11.Tapping off for annealing