This unique technology originated at the turn of the 20th century. For the decorative painting of glass, pure gold and platinum are used. Gold/platinum are applied in a liquid state by a brush and then baked in special electric or gas ovens.
After completion of the baking process, the layer of gold (or platinum) is covered with a matte foundation to protect the gold (or platinum) against abrasion, and another burning in a glass oven follows. Afterward, relief layers in the shape of arabesque and flower motifs are gradually applied. The process of application and burning is usually repeated four times and, in the case of more complex motifs, more times.
Glass colors are pulverized low-melting glass. The painter mixes the corresponding color thoroughly with a binding agent, applies it onto clean glass and burns it (according to the type of color and glass) in a temperature between 470 – 580 degrees. Longer experience is necessary to create more complex decors but most importantly, the painter must have creative feeling, experience and abilities.
The technology of engraving and grinding was adapted from a similar activity with gemstones performed in the court of Rudolf II. Thus, it is possible to grind thick-walled glass, which improves and deepens gravure created by means of a copper roundel. Bohemian engraved and grinded glass became an ideal type of baroque pottery and souvenir. Since the end of the 17th century, it appeared on European and worldwide markets and became so popular that it even endangered the Venetian glass business. At that time, the quantity of glass grinders and engravers increased fast. Nowadays, one could think that glass grinding is a matter of the past, a piece of Czech history. On the contrary – only the technologies have changed, and original materials were replaced by new ones. In general, art and the craft of grinders remained and their work is, just like before, highly appreciated worldwide.
The technology of machine grinding is quite new in the area of glass decoration. This decorating is executed on a machine controlled by a computer and can be complemented by various technologies of painting. This method of decoration is suitable for extensive series of products where a lower price must be achieved compared with manual grinding.
The glass is manufactured in glass ovens by means of melting. During melting, the glass batch melts thoroughly in high heat. Melted glass is inflexible, non-uniform and non-transparent with bubbles that must be removed by increasing the temperature and adding various clarifying substances. The mass is further mixed, bubbles disappear and the glass becomes thinner and more transparent. This procedure is called purification.
Purified glass is very thin. Before further processing, it must be cooled down. Upon manual manufacture, the glass-makers dip the end of the nozzle in a glass melt and turn it around to wind a little bit of glass on it. Then they leave the glass melt to cool down a bit and gather more glass melt. This is repeated several times until the needed quantity of glass melt is gathered. Next, a small bulb is blown from the glass melt and turned around until achievement of an even shape. This glass shape is then stretched by means of pliers and oscillated until achievement of an oblong shape. The bulb is then placed in a form (wooden or metal) and further processed by blowing.
Production of crystal-cur chandeliers has a long tradition in Bohemia. In 1724, glass grinder Josef Palme acquired a license for manufacture of chandeliers and a workshop originated in the small village of Prácheň, where chandeliers were made. Original Bohemian crystal was lead-free with a clear undistorted refraction of light. When one realized that the addition of lead monoxide improves optical characteristics, lead-containing crystal originated. The presence of lead softens glass and thus enables easier graving and grinding. The lead causes a refraction of light and thus fragmentation of light beams into iridescent colors. Lead-containing crystal contains more than 24% of lead monoxide.