Glossary - A Glossary of Basic Terminology Regarding Bohemian Crystal Production

Posted by Radka Volhejnova on

  • Art Deco

A decorative, mainly architectural, style that spread in the Czech lands in the first third of the twentieth century. Unlike the more rigid functionalism, Art Deco put its emphasis on decorativeness and detail. The influence of Art Deco on Czech glass producers during this period is notably apparent.

  • Art Nouveau/Secession

An artistic style of the turn of the nineteenth and twentieth century. It’s particular characteristic is high decorativeness, ornamental elements and fluid curves. Attributes of this originally architectural style found their way into the Czech glass of the time. Czech painter Alphonse Mucha was among the leaders of Art Nouveau.

  • Baroque

An artistic style born in Italy at the end of the sixteenth century. In the following decades, it affected the culture of all Europe. Baroque is distinctly decorative, lavish and opulent. Czech glass had its heyday during the Baroque period, when it managed to overshadow even the then most famous Venetian glass.

  • Benedictines

The Order of St. Benedict, is the oldest order of Western Christianity. In Bohemia, it gained renown for its production of stained glass windows for churches and monasteries, beginning in the ninth century A.D.

  • Biedermeier

An artistic style of the first half of the nineteenth century, typical of the townsmen’s society that was on the rise at the time. The style emphasizes the love of home and cuteness, appropriateness and intimacy and its aesthetic corresponds with that. Particularly painting on glass was developing in this period.

  • Blank

The plain undecorated piece of glassware or crystal which will be further processed to be decorated, engraved, cut and polished.

  • Blown Glass

Glass produced using glassblowing pipes. The blower uses the end of the pipe to pick up molten glass, then blows the glass into a glassmaking form, where the object obtains its final shape.

  • Bohemian Crystal

Transparent glass that resembles natural quartz in appearance. It is greatly suited for various decorations and treatments. This glass first appeared in the Czech lands in the sixteenth century. Its popularity peaked at the turn of the seventeenth and eighteenth century, when it entirely overshadowed Venetian glass across Europe.

  • Barium Glass

When barium oxide is added to the basic glass mixture, the result is a product of superior clarity, strength and resiliency. Barium glass is primarily used in the production of those stemware lines which have a long, slender stem, or relatively thin-wall bowls.

  • Cameo Engraving

A figure or design is engraved in relief on to glass cased with one or more layers of colored glass. The engraved pattern is cut away the under layers provide a contrasting background.

  • Cased Glass

Glass with one or more colored layers. As the engraver cuts through the layers, the different colors are revealed. Various shades can be achieved by skillful control of the depth of cut.

  • CRYSTAL

 A much abused term which in the trade, simply refers to a clear colourless glass. The general materials used to produce crystal are fine silica sand, potash, and cullet (broken pieces of glass which are essential for the batch mixture). Other materials can be added to the basic batch mixture, such as oxides, i.e. lead oxide, gold oxide, barium etc.

  • CRYSTALITE

This is glassware which achieves the brilliance similar to lead crystal through the use of alternative minerals. It allows the glass to be more clear and brilliant as well as allow some forms of cutting and etching. Crystallite does not have a lead content.

  • CUTTING, ENGRAVING AND ETCHING

Cutting, engraving or etching on glass or crystal are three completely separate techniques of decorating glassware. The easiest way to distinguish between the three techniques is that cutting is a “wet process”, while engraving and etching are relatively “dry processes”. A diamond-carborundum wheel is used for cutting glass crystal and a continuous stream of water during the cutting process ensures the tiny glass particles are removed. Engraving is done generally with the use of a small copper wheel which produces a “shallow cutting” into the surface of the product. A small amount of abrasive fluid (not water) is used in order for the wheel to move more smoothly over the surface and scratch the design into the piece. Etching can be done with a laser or acid process.

  • COLOURED CRYSTAL

Colour is introduced into the glass by the addition of various oxides to the basic batch mixture. Gold oxide (as well as chrome oxide) is used to produce the ruby colour, this is the reason why ruby glass is generally more expensive. Iron oxide produces a green colour, cobalt oxide produces blue glass and the addition of uranium oxide will produce an amber or yellow colour. It should be noted that generally, colour is found in non-lead crystal products, but may also be used in glass which covers full lead crystal. MOULDS Both wooden and cast iron moulds are used in the production of crystal/glass products. Although, the wooden moulds are produced from hardwoods (Cherry and Beechwood), they must be replaced more often as they burn-out after time despite being immersed in water.

  • Definition of Crystal

Although nowadays, according to industrial standards, crystal in Europe is understood to be only leaded glass, the term crystal is used for all glass that is close to natural quartz in its unique physical properties and optical characteristics – high luster and transparency. Crystal can also be a lead-free glass.

  • Forest Glass

The oldest hand-blown glass typical for countries above the Alps. It was produced in the Middle Ages in glassworks located in forests (hence its name) and is characteristically green-tinted due to imperfect purification of the materials. It also features random and tiny air bubbles.

  • Functionalism

An artistic, particularly architectural, style of the first third of the twentieth century. Its characteristics are stylistic restraint, simplicity and austerity. After 1930 these attributes were, for the first time in history, also implemented in Czech glass.

  • Glassblowing Mold

A mold created from high-quality wood used to shape molten glass blown into the mold by the glassblower. The mold is carefully produced according to a technical drawing and its basic shape is a hemisphere. Each wooden mold lasts only 50 glasses, then a new one must be hand-curved.

  • Glassblowing Pipe

A basic tool for the production of blown glass. The glassblower picks dips the end of the pipe in molten glass and blows it into a form or works it with other tools. The oldest documented glassblowing pipes were used by the Phoenicians, several thousand years before Christ.

  • Glassworks

An industrial establishment appointed for the production of glass. Its core is a glassmaking furnace which melts the materials necessary for glass production, as well as other buildings necessary for material storage and further production.

  • Glyptics

The art of engraving precious stones and semi-precious stones. One of the oldest artistic techniques that came to Czech lands thanks to the King and Emperor, Rudolph II. It was glyptics that began engraving pure glass, becoming the first glass cutters and engravers.

  • Guilloche

This is an identical procedure to pantograph, but there is only one needle used, producing simple geometric patterns which are continuous.

  • High Enamel

Although painting on glass was already common in ancient times, the technique of high enamel was created at the end of the eighteenth century and fully developed in subsequent years. Applying precious metals on glass had both the goal of making the glass more attractive and to hide possible imperfections in the materials. It enabled the production of large pieces with likely impurities in the glass.

  • Intaglio Engraving

A decorative technique where the design is engraved deeply into the glass, but appears to give the opposite effect.

  • Lead-free glass

A silica glass without the content of lead monoxide and therefore not harmful to the health of glassmakers as well as those later processing the glass and also more environmentally friendly. Lead-free glass is more brittle than leaded glass but the same decorative techniques can be used on it. CLARESCO Glass strictly uses only lead-free crystal for its products.

  • Lead Glass

Glass enhanced by the addition of lead monoxide that lends it properties desirable for further processing. Leaded glass is an English invention and is easy to work with, causing the glass to become softer, adding luster and making it perfectly suitable for cutting.

  • Lead Cystal

When lead oxide is added to the basic glass mixture, “lead crystal” is produced. The amount of lead oxide added, determines the classification of the crystal, as well as the strength and malleability of the crystal. It also enhances the brilliance and clarity of the glass. Semi-lead crystal (crystalline) contains approximately 8 -10% lead oxide, while the term “full lead crystal” is generally conceded to contain a minimum of 24% lead oxide. Lead oxide was initially introduced into crystal by the English approximately 250 years ago, due to the fact that it has a low melting temperature (1000 – 2000 degrees Celsius). Lead oxide also adds brilliance to the product when cut. It should also be noted that the most important reason for using lead oxide, is to soften the glass and, therefore, facilitate cutting and engraving on the item as a means of decoration. There are obviously disadvantages of having a softer glass product, i.e. it is more unstable during temperature changes; if softer, then it tends to chip or scratch much more easily.

  • Melting

The production of glass from glass mixtures, using various substances. The basis of the mixtures is silica sand, calcium oxide, sodium oxide and potassium oxide. The mixture is first ground and thoroughly blended, then liquefied at temperatures ranging from 1450–2000o C in glassmaking kilns. The ratio of the individual components determines both the physical and optical properties of glass.

  • Mold-Blown Glass

The shape of the finished article is achieved by glass being blown into a wooden mold. The mold may be used simply to shape the glass or to impress patterns upon it.

  • Murano

A series of islands located approximately a kilometer and a half from the Italian city of Venice. Murano is known for its traditional production of Venetian glass. Beginning in 1921, all local residents and producers were isolated there in order to keep the method of their glass production secret.

  • Pressed and Over Cut

 This refers to an item, generally produced in lead crystal, that has had initial base cuts pressed using a mould. The piece, however, must be finished with fine hand-cutting by a master cutter in the same manner as a completely mouth blown item.

  • Pantograph

This is a technique in which a clear glass is dipped and covered in a mixture of paraffin and bee’s wax. Then the glass is placed on a machine which has four needles surrounding the glass. An operator traces a stencil which is hooked to the machine and wherever the operator traced, so too, do the four needles and thus they remove the wax leaving a design. The glass is then taken and placed in an acid solution for anywhere from 7 to 40 minutes depending on the size of the piece and acid concentration. In this process only the areas uncovered by wax are eaten away (the design area) and the wax is removed later by hot water to be reused.

  • Relief Engraving

The removal of the background of a pattern on glass to leave the design embossed forward, as with a head on a coin.

  • Silica Sand

The basic material in glass production. Prior to melting, this mineral with a high content of silicon dioxide or other chemical admixtures must first be treated and cleaned. The first Czech glassworks were established in areas abundant with these materials.

  • Silk Screen Print

A graphic technique based on pressing ink through a screen template. Silk screen can be used to decorate many different materials, including glass. Silkscreen on glass is among the most technically challenging decorative techniques.

  • Stained-Glass

This is a glass mosaic set in lead frames used for glazing windows. This use became widely spread during Middle Ages, particularly in sacral architecture. In the Czech lands, the first stained glass windows were produced by the Benedictines.

  • Vitus Cathedral

The most famous and important sacral building in the Czech Republic. It was built upon the initiative of Czech King Charles IV and its construction continued until the twentieth century. It is particularly important for the history of Czech glass due to the monumental Mediaeval glass mosaic of the Last Judgment, composed from a million glass components. The cathedral is also decorated with outstanding stained-glass windows from the time of the First Republic, from the painter Alphonse Mucha, among others.

  • Technical Drawing

Practically all basic techniques from producing a wooden glassmaking mold to glass decoration are based on precise technical drawings.

  • Template

A paper tool used in glass production for various decorative purposes. A template helps the artist in sandblasting, painting and engraving, as well as cutting glass decors.

  • The First Republic

One of the happiest and most productive periods in the history of the Czech lands. It is dated by the formation of independent Czechoslovakia in 1918 and the beginning of WWII. The period was characterized by enormous economic and cultural growth, during which today’s Czech Republic belonged among the top-ten richest per capita countries in the world.

  • Venetian Glass

The expression Venetian glass (in Italian vetro veneziano) refers to the oldest glass manufacturing in Europe, dating to the second half of the first millennium in Italy. By the Middle Ages, Italian glass production was centered and isolated at the island of Murano, from where its glass products dominated the world until the fifteenth century.


0 comments

Leave a comment

Please note, comments must be approved before they are published