The Making of Crystal Glass

	Gathering Molten crystal glass collected from a refractory melting pot by rotation of metal blowpipe.
Mouth blowing The article becomes hollow and expands as the craftsman increases blowing pressure.
	Shaping the foot A separate piece of molten glass is added and spun with pearwood.
Shearing Removing surplus glass and levelling the top after welding the foot to a steel rod.
	Shaping the edge Glassmaker’s tools controlling the shape as the article is spun.
Adding the handle A separate piece welded at the base, sheared to length, attached with pincers.

Composition

Both lead crystal glass and full lead crystal glass are made from a mixture of sand, potash and lead oxide. There is a British Specification (BS 3828: 1964) for each type. Lead crystal glass contains a minimum lead oxide content of 24 %, and is manufactured primarily for its beauty of appearance, particularly when decorated by a skilled glass cutter. Full lead crystal glass contains an even higher proportion of lead oxide, in fact, not less than 30%, which greatly enhances this beauty although it is more costly to produce.

The Glass House

The scene presented by the glass-house while the work of glass-making is in progress is full of interest and fascination. Men are engaged in groups around the furnace where the glass is melted, performing, in the glow from the crucibles, the complicated, masterly, and often graceful motions of their craft. Each group is known as a “chair” and consists of four or five persons: the “workman”, who is the principal, two who are known as “foot-maker” and “servitor” - and one or two boys who are employed in performing minor operations, and carrying finished articles away. A certain part of the work is apportioned to each member of the group, according to the design of the article on which the “chair” is engaged.

To begin, a ball of molten glass is gathered from the pot on the end of the blow-iron, which is a steel tube about four feet long. It is continuously rotated in order to distribute the glass evenly. The gathering of glass is next rolled on a polished iron table, called a “marver”, to smooth and regularise the surface. The glass-worker now blows through the tube, and the hot glass becomes a hollow sphere, the blow-iron being turned, tilted and swung in a way which almost magically influences the shape which is developing. The glass is further shaped as the iron is rolled up and down on the long arms of the glass-maker’s chair. A few very simple tools are used - such as steel pincers, callipers, shears, wooden measuring-sticks and clappers.

The stem and foot is now added, and the object is transferred for further working to a “pontil”, or steel rod, to the end of which it is attached by a blob of hot glass. Remelting is necessary before superfluous glass is sheared away from the rim and the final touch given. The still glowing object is cracked off the rod, dropped into a carrying apparatus and transported swiftly to the annealing oven or “lehr”.

Annealing

The lehr, or annealing chamber, is a long tunnel down which the glass is conveyed slowly, passing gradually from a high temperature to the coolness of the ordinary atmosphere. This is necessary because, if the glass were allowed to cool rapidly, it would probably shatter owing to the strains and stresses within it. On removal from the lehr each article undergoes a searching examination for flaws. At this stage a scientific instrument is brought into play which reveals by means of polarised light any trace of imperfect annealing.

The Decorating of Crystal Glass

Marking	Cutting
Engraving

Cutting

This is done by holding the glass against the edge of a revolving wheel precisely in the manner described by the Roman historian, Pliny, with only this difference, that the wheel is turned for the modern cutter by electricity. It sounds a very simple process, but actually it calls for a very high degree of skill. The glass must be cunningly guided to produce some of the lovely and intricate effects that are possible. There is an infinite number of patterns and combinations. Some of these have curious and interesting traditional names such as “diamonds”, “laced diamonds”, “hobnails”, “splits”, “fans”, “flutes”, “stars” and “jewels”.The finest of wheels may cut some hundreds of diamonds to the square inch in a pattern of fairy delicacy, or the design may have a massive architectural simplicity and consist of only a few bold cuts and broad facets. The pattern, which has been indicated on the glass “blank” by specially trained markers, is first roughly cut on a carborundum wheel fed with water. The next frame carries a synthetic or quarried stone wheel fed with water, which has a much finer abrasive action, and smooths the rough cuts made by the carborundum wheel. The glass is now ready for polishing.

Polishing

Polishing is done by immersing the glass in a vat containing a mixture of hydrofluoric and sulphuric acid. About a minute’s contact with these highly corrosive chemicals and a thorough rinse afterwards transforms glasses with matt decoration into sparkling pieces of either Thos. Webb or Edinburgh Crystal.

Copper Wheel Engraving

In a modern glass factory engraved designs are produced by various techniques such as sand etching, diamond point and copper wheel engraving. Each of these techniques has a unique quality and it is not unusual to see these processes combined to great effect. Copper wheel engraving is one of the oldest decorating techniques and a long period of training is necessary to develop the skill required to hold a glass against a small revolving copper wheel, moistened with abrasive, to produce an engraved design. Pictorial designs commemorating a public or private event have always been popular. Whether initial letters and a date, or a richly ornamental piece to mark a royal occasion, engraved glass has a special place in the history of fine glassmaking.

Edinburgh Crystal

Shown in The Glass Catalogue here

A goblet made in a limited edition to commemorate the American Bi-centenary in 1976.

Edinburgh Crystal

Shown in The Glass Catalogue here

A goblet made in a limited edition to commemorate The Queen’s Silver Jubilee in 1977.

Characteristics of Crystal Glass

It is quite normal for people to wonder why small irregularities cannot be eliminated entirely from hand-made crystal glass. The answer lies in just that very fact -that it is hand-made. No matter how deft the touch of the sensitive hand of crafts­men, it is impossible to eliminate small variations. They should not be regarded as defects. Glass is one of the most difficult materials with which to work, and even machine-made glassware cannot be absolutely perfect. When a person thoroughly understands the characteristics of really fine crystal glassware, he seeks the hallmarks of either Thos. Webb or Edinburgh crystal.

A Seed or Bubble

During the fusing and melting of the raw ingredients which form Lead Crystal, gases are evolved and air between the particles is entrapped. During the refining process nearly all these seeds or bubbles are removed. Small isolated ones sometimes remain and should not be regarded as flaws. When two pieces of crystal are joined together during the making of an article a small air bubble may be encased. Wherever possible, this inclusion is avoided, but in some cases it must be regarded as inherent in the product.

Uniformity

Strange as it may sound, slight variations in dimensions are the hallmark of fine hand craftsmanship. Absolute uniformity can be achieved only in assembly-line products and it is not possible or even desirable, in quality ware, which depends so much on the skill and artistry of individual craftsmen.

Hand-made or Hand-finished?

A customer may ask if hand-made glassware is really made by hand, or is it merely hand-finished? The production of hand-made glassware definitely is a hand process and requires the co-ordination of the skilled hands and eyes of many men, working in teams. It is a point of pride in the industry that variation between articles of the same shape and size is extremely small.

Cords

When glass is perfectly homogeneous it does not contain cords. However, in practice, this state of absolute perfection is rarely achieved and slight differences in refractive index occur which are visible to the naked eye. Unless the effect is very pronounced it should not be regarded as a defect.

Mould and Tool Marks

These are sometimes apparent on the surface of the article and, if slight, should not be looked upon as imperfections. The marks will not in any way affect the longevity of service of the piece.

Shear Marks

The artisan frequently snips off excess glass when shaping the piece whilst molten. Slight marks from the shears can frequently be seen around the edge of handmade articles, and at the end of the handles of jugs. These marks are a normal characteristic of the glass and are not flaws.

Care for your Crystal

Tests by the British Glass Industry Research Association have shown that repeated washings in automatic machines with detergents or very hot water can destroy the surface of any glassware. It is recommended that glassware, and particularly lead crystal, should be washed by hand with warm water and soap or any suitable household detergent.