Blown plate was made from broad sheet glass by laboriously hand grinding and polishing both surfaces.
By varying its composition, texture, and color, glass can be made translucent or opaque.
The process of making stained-glass windows involves cutting colored glass into different shapes, assembling the pieces (using lead came strips or copper foil), soldering them together, and installing them in a frame.
The glass is then rapidly cooled with forced drafts of air, causing the surface to harden and contract, while the inner portion of the glass remains soft for a short time.
Another technique is to manipulate glass in a kiln.
Laminated glass, invented in 1903 by French chemist Edouard Benedictus, is a type of safety glass that holds together when shattered.
Due to the balancing of stresses in the glass, any damage to the edges will cause the material to shatter into thumbnail sized pieces.
Glass objects from the seventh and eighth centuries have been found on the island of Torcello near Venice.
A similar glass is often used for the front windows of airliners.
The glass floats on the tin and levels out as it spreads over the bath, giving a smooth glossy face to both sides.
Scientists can now make glass vessels in which biologically active molecules, such as enzymes, are embedded.
When gem-cutters learned to cut glass, they found that clear glass was an excellent refractor of light, causing the glass to sparkle.
The impetus for this new modern glass was the restoration of thousands of church windows throughout Europe, destroyed by World War II.
The stability of glass also means that it does not break down in the environment.
Some of the different types of glass produced by these processes were known as crown glass, broad sheet, cylinder blown sheet, blown plate, and polished plate.
The glass is then annealed in a lehr.
Glass is also valuable for making lenses, with surfaces that are convex, concave, planar, or a combination of these types.
The word glass may be defined as an amorphous solid that is usually produced by mixing silica with other chemicals at high heat, and allowing the mixture to cool without forming a crystalline structure.
Often the glass is colored during the production process, but sometimes it is painted.
Undersea cables have sections doped with erbium, which amplify transmitted signals by laser emission from within the glass itself.
Glass art includes the creation of stained glass, working glass in a torch flame (lampworking), glass beadmaking, glass casting, glass fusing, and creating artistic shapes through glass blowing.
Most large laboratories need so much custom glassware that they keep a glassblower on staff.
Around 1688, a process for casting glass was developed, and the material became much more commonly used.
Preparation of this type of glass, however, cannot be carried out by the usual, high-temperature methods, because the heat would destroy the enzymes.
Polishing the edges or drilling holes in the glass is carried out before the toughening process starts.
The glass was made from sand, plant ash, and lime (calcium oxide).
Ordinary glass, on the other hand, absorbs (and blocks) UV radiation.
Additional ingredients may be added to produce glass in a wide range of colors (see below).
Glass in buildings can be of a safety type, including wired, toughened, and laminated glasses.
Laminated glass is normally used when there is a possibility of human impact, or if the glass could fall if shattered.
At low concentrations (0.025–0.1 percent), cobalt yields blue glass.
Glass has been used in buildings since the eleventh century.
Glass is chemically stable and unreactive, and retains its shape and structural integrity at ordinary temperatures for long periods.
The term "crystal glass" (derived from rock crystal) is currently applied to high-quality, colorless glass, often containing lead, but it is occasionally used in reference to any fine, hand-blown glass.
Pure silica glass (also called fused quartz) does not absorb ultraviolet (UV) light and is used for applications that require transparency in this region.
Toughened glass (or "tempered glass") is a type of safety glass that is typically four to six times the strength of annealed glass.
Glass has been considered a valuable material since early in human history.
Stained glass is now available in a variety of textures that alter the color transmission characteristics of the glass and produce surprising effects.
The glass is placed on a roller table, taking it through a furnace that heats it to above its annealing temperature (600 °C).
Prior to the twentieth century, various methods of making hand-blown glass were developed.
The color of "natural glass" usually varies between green and bluish green, based on the differing amounts of naturally occurring "impurities" of iron in the sand.
Decorative items made of glass include vases, bowls, chandeliers, sculptures, paperweights, beads, and marbles.
After centuries of repetition and little innovation, stained glass underwent a major renaissance of form.
Traditional stained glass work is commonly called cold glasswork.
During the Stone Age, flint knappers used obsidian, a naturally occurring glass, to make extremely sharp knives.
Machine drawn cylinder sheet was the first mechanical method for "drawing" window glass.
The PVB interlayer also gives the glass a much higher sound insulation rating, due to its damping effect, and blocks 99% of transmitted UV light.
Nickel, depending on its concentration, produces blue, violet, or even black glass.
Artistic patterns are sometimes etched into glass using an acid or other caustic substance (which "eats" into the glass).
Consequently, the popularity of cut clear glass soared, while that of colored glass diminished.
Retail stores use glass cases to display as well as protect their products for sale.
The early twentieth century marked the move away from hand-blown to machine-manufactured glass, such as machine drawn cylinder sheet, rolled plate, and float glass.
From this point on, northern glass differed significantly from that produced in the Mediterranean area, where soda remained in common use.
Uranium (0.1–2 percent) can be added to give glass a fluorescent yellow or green color.
One common misconception is that glass is a "super-cooled liquid of practically infinite viscosity" when at room temperature.
Occasionally, such glass has been found thinner side down, probably as a result of carelessness at the time of installation.
The way the glass is heated and cooled can significantly affect the colors produced by these compounds, but the chemistry involved is complex and not well understood.
Glass is an extremely useful material, serving both practical and artistic needs.
Broad sheet glass was made by blowing molten glass into an elongated balloon shape with a blowpipe.
Traditionally, this was done by a trained artisan after the glass was blown or cast.
When broken, chemically strengthened glass still shatters in long, pointed splinters, similar to float glass.
Pure, metallic copper produces a dark red, opaque glass, and it is sometimes used as a substitute for gold in the production of ruby-colored glass.
Glass can also be cut with a diamond saw and polished to give gleaming facets.
Glassmakers learned to make colored glass by adding metallic compounds and mineral oxides to produce brilliant hues of red, green, and blue—the colors of gemstones (see Ingredients for colors below).
The process involved blowing the glass into spheres, swinging them out to form cylinders, cutting them while still hot, and then flattening the sheets.
Metallic gold at low concentrations (around 0.001 percent) produces a rich, ruby-colored glass, and at lower concentrations it produces a less intense red, often marketed as "cranberry."
Toughened glass is made from annealed glass via a thermal tempering process.
Large amounts of iron are used in glass that absorbs infrared energy, such as for heat-absorbing filters in movie projectors.
Pure silica glass is also used to make fiber optic cables that can transmit light over long distances and are therefore useful for the telecommunications industry.
The molten glass is then annealed in a furnace to produce sheets of colored glass.
Selenium, likewise, can be used at low concentrations to decolorize glass, but at higher concentrations, it imparts a reddish color.
The oxides of tin, antimony, and arsenic produce an opaque white glass, first used in Venice to produce an imitation porcelain.
Drinking glasses, bowls, and bottles are often made of glass, as are light bulbs and mirrors.
The main constituent of glass is silica (SiO2).
When installed in a window frame, the glass would be placed thicker side down for the sake of stability and visual effects.
Cerium(IV) oxide can be used for glass that absorbs ultraviolet (UV) radiation, which damages DNA and living tissue.
Uranium glass is typically not radioactive enough to be dangerous, but if ground into a powder (such as by scraping with sandpaper) and inhaled, it can be carcinogenic.
Glass-making technologies have developed over many centuries, and the properties of glass can be modified significantly with the addition of various compounds, heat treatment, and other techniques.
Bulletproof glass panels, made up of thick glass (often toughened) and several interlayers, can be as thick as 50 mm.
New shades of colored glass are frequently discovered.
One important technique is called lampworking, in which the glass is melted with a flame and reshaped.
Begun in Eastern Asia and among Muslim designers, the art of stained glass reached its height in the Middle Ages, particularly 1150-1250.
Glass with a wide range of colors can be produced by adding different metals and metal oxides during the manufacturing process.
The glass surface goes into a state of compression, while the core is in compensating tension.
Instructions to make glass were first documented in Egypt around 1500 B.C.E., when glass was used as a glaze for ceramic items before they were fired.
The glass is then annealed (held at a temperature at which internal stresses are relieved) and cut into 7–10 foot (2–3 meter) cylinders.
Various techniques have therefore been devised to strengthen glass (see Specialty glasses below).
Discarded glassware needs to be properly recycled in order to avoid the buildup of trash.
Shop front glazing and automobile windshields are typically laminated glasses.
Many of Archimedes’ works were lost when the Library of Alexandria was burnt (twice), and survived only in Latin or Arabic translations.
The process for making crown glass was first perfected by French glassmakers in the 1320s, notably around Rouen.
The glass-pressing machine was invented in 1827, allowing the mass production of inexpensive glass articles.
From tiny beads to large sculptures, and from ordinary bottles to sophisticated lenses and optical fibers, the multiple uses of glass have transformed our world.
The eleventh century saw the emergence, in Germany, of a new approach to making sheet glass.
Important contemporary artists who have produced painted glass objects include Judith Schaechter and Walter Lieberman.
The presence of soda, however, also makes the glass water soluble, which is usually undesirable.
Scientific research laboratories are equipped with flasks, test tubes, beakers, thermometers, measuring devices, and other pieces of apparatus made from glass.
At the time of the Roman Empire, many forms of glass were created, usually for vases and bottles.
The artistic uses of glass are discussed under Glass art.
Foamed glass, made from waste glass, can be used as lightweight insulation.
Stained glass is an art form with a long history.
Toughened glass (or "tempered glass") is a type of safety glass that is typically four to six times the strength of annealed glass.
Lenses are useful for such things as magnifying glasses, eyeglasses, cameras, microscopes, binoculars, and telescopes.
Some famous artists in glass include Lino Tagliapietra, Rene Lalique, Dale Chihuly, and Louis Comfort Tiffany.
Cylinders of glass 40 feet (12 meters) high are drawn vertically from a circular tank.
To make float glass, several raw materials—sand, limestone (calcium carbonate), soda ash (sodium carbonate), dolomite (calcium magnesium carbonate), iron oxide, and salt cake (sodium sulfate)—are mixed together and melted in a large furnace.
The piece is then fired in a kiln, causing the oxides to fuse permanently with the glass.
The quality of broad sheet glass was not good, with many imperfections.
Early artists working with stained glass were limited to a few primary colors, but today almost any color can be produced.
A typical laminated makeup would be 3 mm glass / 0.38 mm interlayer / 3 mm glass, referred to as "6.38 laminated glass."
One of the most obvious characteristics of ordinary glass is that it is transparent to visible light.
Great ateliers like Tiffany, Lalique, Daum, Galle, the Corning schools in upper New York State, and Stubbe glassworks have taken glass art to its highest levels.
Multiple laminates and thicker glass increases the strength.
The resultant glass contains about 70 percent silica and is called soda-lime glass.
From the fourteenth century onward, the center for glass making was Venice, where many new techniques were developed.
"Naturally the Mona Lisa is a carefully watched and protected painting. It is kept in a special sealed box to protect it from vibrations, heat and humidity. It is protected by thick glass resistant to bullets and any other object hurled at it," he said.Aug 11, 2009
6) Lightning can travel through pipes so avoid all plumbing during a thunderstorm. That means no washing your hands, showering or washing dishes. 7) Stay away from any windows. Lightning has been known to strike through glass.Jun 20, 2011
Hyalinobatrachium dianae, also known as Diane's bare-hearted glass frog, (or a Kermit frog due to its peculiar appearance) is a species of Costa Rican glass frog in the family Centrolenidae.