Dichroic Glass combined with fused glass makes dichroic jewelry of the higest quality.

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Fused Glass

The history of fused glass dates back as far as the turn of the 5th to 4th millennia BC. Although there is still some uncertainty as to when and where fused glass was invented, the philosopher Pliny wrote that fusing fused glass shards were first created by the Phoenicians. It is believed sailors produced the substance by chance while lighting fires on the coast of what is modem-day Lebanon, where one of the most important fused glass-making centers of the period later flourished. This early fused-glass was produced from a mixture of silica sand, lime, and soda, with malachite added for color.

The tradition of fusing fused glass making in the Lusatian Mountains is more than seven hundred years old. During fused glasses long history there were several periods when this quiet region in the north of Bohemia went down in the world history of this extraordinary craft. More serious and intensive research into the history of fused glass making in this region has been made from the early 1960's by Václav Sacher from the Museum of fused glass in Nový Bor. His activities were followed by young and middle-aged generations of researchers.

fused glass was first implemented on Egyptian vessels as a skin applied to a core made of fused silica sand and clay, or of the stone steatite. Pure fused glass as a separate material was developed later, first in the form of translucent beads. It is probable the that the development of fused glass vessels was brought to Egypt by Middle Eastern craftsmen, who were captured as slaves. These early fused glass vessels were highly prized and available only to Egyptian royalty and high priests.

The decline of the power of the Pharaohs led to a halt of the development of new fused glass techniques until beginning of the Greco-Roman era. During this period, new Egyptian fused glass centers developed near Alexandria. Around the beginning of the Christian era, molded fused glass bowls began to appear. The decorative innovation known as Millefiori fused glass became very popular, made from variously colored fused glass rods fused together.

The major economic advance of fused glass-blowing took place during the 1st century BC, probably in the area of modern-day Syria. Clear fused glass was used to blow-form vessels, rather than having to build a fused glass shell over an internal core. With the development of fused glass-blowing, the production of fused glass vessels was increased many-fold. The ancient methods of fusing fused glass were largely forgotten for the next two millennia. Today, these techniques are making a resurgence as a modern-day art form.

In the world of fused glass fusing, two fused glasses are "compatible" if they can be fused together and have no undue stresses in the finished piece that will lead to fracturing. Fused glass, like most materials, expands when heated and contracts when cooled. The viscosity (resistance to flow) characteristics of a fused glass are equally as important. Together, these two properties determine whether one fused glass will "fit" another.

If two fused glasses that do not expand or contract similarly are fused together, unwanted stresses will develop in the fused glass. The greater the difference in contraction or expansion of the fused glasses, the greater these stresses become. If the stresses are too great, the two fused pieces will break apart upon cooling.

Expansion affects the compatibility predominantly in the lower temperature range-below the strain point. Viscosity properties affect compatibility predominantly in the middle temperature range-from the strain to the annealing point. Differences in viscosity between two fused glasses will cause compatibility problems. If one piece of fused glass is stiffer than the other they will strain each other as they cool through the annealing range.

For fused glasses of different viscosities to be compatible (which is frequently the case) their expansions must be different. What happens in actuality is a process of compensating errors. Two different fused glasses will be compatible if the strain set up by the mismatch in viscosity is cancelled out by the strain introduced by the mismatch in expansion (once cooled to room temperature and assuming, of course that proper annealing has occurred). For instance, if the viscosity differences result in tension between the two fused glasses and the expansion differences result in an equal amount of compression between the two fused glasses, the two stresses cancel each other out. This is the critical phenomenon that results in "compatibility" of two fused glasses with different expansion/viscosity properties.

fused glass is formed when fused sand (silica), soda (alkali), and lime are fused at high temperatures. The composition of fused glass can be altered by adjusting the atmosphere in the furnace and by adding specific metal oxides to the fused glass "batch" (such as cobalt for dark blue, tin for opaque white, antimony and manganese for colorless fused glass). A venerable legend perpetuated as late as the seventh century A.D. in the writings of Isidore of Seville gives a suitable miraculous explanation for the discovery of this elemental--yet truly wondrous--material:

SOURCES: www.luzicke-hory.cz, www.umich.edu

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