traditional technology
GLASS OR CRYSTAL? The word crystal was used in the past to indicate top quality glass, and therefore the balance of appearance, shine, clarity, and bright colour. Under no circumstances was the word used to denote chemical components. The situation is different today and, in relation to the standardisation of names within the European Union, a regulation use of the word “crystal” came about at the end of the 1960s. This set forth a precise determination of material labelled as such that is based on its components, refraction index, and density, but not on the strength of overall optical qualities, such as purity, optical and chemical homogeneity, content of bubbles, or optical brilliance. According to the valid definitions, the glass used in the production of clear products under the “Desná” label is crystal glass, classified in the fourth group of Regulation No. 379/2000 of the Czech Ministry of Trade and Industry. However, because the components of the material used in “Desná” products are not the most important characteristics, but the design and the overall quality, we label our basic material as “glass” in accordance with tradition.
The range of products included under the “Desná” label is interesting both from a creative and a technological perspective. That is to say that utility and decorative glass objects are produced on the basis of demanding traditional procedures, which differ from the original methods of production in only a few minor details. The foundation of production success is the melting of quality glass that is not susceptible to solarization. Apart from this, the other necessary conditions are hand work and a team of experienced professionals comprising glassmakers, smelters, cutters, technologists, metal workers, and other professions whose expertise is highly specialised, mainly connected directly to the glassworks, and requiring of long-term practical preparation.
The basic shape of the product is the result of pressing or blowing. Objects with closed shapes, most often bottles and scent bottles, are blown into metal moulds by the glassmaker. Pressing is primarily used during the production of objects with an open shape, such as ashtrays, candleholders, and figurines.
Aside from the hand cutting of products, the frosting of products is an often-used finishing technique. The character of the frost is usually selected individually according to the character of the particular products. It is so delicate in many cases that it effects a silky shine. This is the result of a chemical process that creates an “icy” coating on the surface of the finished product. The combination of polished surface and frosted embossing is typical for a number of popular products in the “Desná” range.
“Desná” products are primarily produced from clear glass with special components. This glass is the result of long-term development that responded to changes in melting technology as opposed to classic pre-war production. Nowadays, the molten glass produced is the most appropriate molten glass for the artistic glass ware products of the Jablonex Group a.s. thanks to its hardness and chemical and optical qualities.
Transparent colours also make up a special chapter in the “Desná” product range. The transparent colours traditionally used at the Jablonex Group a.s. have been specially developed so that they create the anticipated optical effect on heavy glass. For this reason they are very delicate and labelled as so-called Jizera colours to ensure their uniqueness. Uranium yellow is historically the colour most associated with the company’s past, since the story has been passed on that it was named as a tribute to the glassmaster’s daughter Anna. This is why it is known as Annagelb (Anna’s yellow). Its peculiarity is that it glimmers brightly under ultraviolet light. In spite of the fact that uranium is used in the production of this colour, it is used in a form that is non-detrimental to health.
Less distinctive, but extremely popular among experts, is noble blue, which is sometimes known as alexandrite. This is a colour that is produced using elements of rare earth. These give the glass its special character, in that the glass appears to be differently coloured in daylight and under artificial light. Another two colours from the range of transparent glass are traditional and peculiar to Desná. The first is noble green, which is characterized by its comforting turquoise tone, and the second is a rosy rosaline.
Most typical of the colouring of Jizera Mountain glass, however, are rich or opaque colours, such as jade (green—inspired by jadeite and malachite) and lapis (blue—inspired by lapis lazuli). They resemble natural semi-precious stones so faithfully that the layperson does not believe that it is glass at all. The special colour transitions and effects of these colours are accomplished both by the components of the glass and by using special procedures in the course of production, which gives an irreproducible and unique character to every individual piece.
