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Milk glass is an opaque or translucent, milk white or colored glass that can be blown or pressed into a wide variety of shapes. First made in Venice in the 16th century, colors include blue, pink, yellow, brown, black, and white.
Milk glass contains dispersion particles with a refractive index significantly different from the glass matrix which scatters light by the Tyndall scattering effect. The size, distribution, and density of the particles controls the overall effect; which may range from mild opalization to opaque white. Some glasses are somewhat more blue from the side and somewhat red-orange in pass-through light.
The particles are produced by the addition of opacifiers to the molten glass. Some opacifiers can be insoluble and are only dispersed in the melt. Others are added as precursors and react in the melt or dissolve in the molten glass and then precipitate as crystals upon cooling. This is similar to color production in striking glasses though the particles are much bigger.
A variety of opacifiers can be used: bone ash, tin dioxide, arsenic, and antimony compounds. These are also added to ceramic glazes which, chemically; be considered a specific kind of milk glass.
Milk glass was first made in Venice in the 16th century (lattimo) as a translucent competitor for porcelain. Colors include blue, pink, yellow, brown, black, and white. Some 19th-century glass makers called milky white opaque glass "opal glass". The name milk glass is relatively recent. [2] [3]
Made into decorative dinnerware, lamps, vases, and costume jewellery, milk glass was highly popular during the fin de siècle . Pieces made for the wealthy of the Gilded Age are known for their strikingly delicate beauty in both color and design while Depression glass pieces of the 1930s and 1940s are less so.
Milk glass is often used for architectural decoration when one of the underlying purposes is the display of graphic information. The original milk glass marquee of the Chicago Theatre has been donated to the Smithsonian Institution. [4] A famous use of milk glass is for the four faces of the information booth clock at Grand Central Terminal in New York City. Barbetta, the New York Italian restaurant founded in 1906 and still in business as of 2022, [5] has what is said to be the last opal glass sign in the city. [6]
Milk glass has a considerable following of collectors. [7] Glass makers continue to produce both original pieces and reproductions of popular collectible pieces and patterns. [8]
In the field of optics, transparency is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale, the photons can be said to follow Snell's law. Translucency allows light to pass through but does not necessarily follow Snell's law; the photons can be scattered at either of the two interfaces, or internally, where there is a change in the index of refraction. In other words, a translucent material is made up of components with different indices of refraction. A transparent material is made up of components with a uniform index of refraction. Transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. The opposite property of translucency is opacity. Other categories of visual appearance, related to the perception of regular or diffuse reflection and transmission of light, have been organized under the concept of cesia in an order system with three variables, including transparency, translucency and opacity among the involved aspects.
A marble is a small spherical object often made from glass, clay, steel, plastic, or agate. They vary in size, and most commonly are about 13 mm in diameter. These toys can be used for a variety of games called marbles, as well being placed in marble runs or races, or created as a form of art. They are often collected, both for nostalgia and for their aesthetic colors.
Fire-King is an Anchor Hocking brand of glassware similar to Pyrex. It was formerly made of low expansion borosilicate glass and ideal for oven use. Currently it is made of tempered soda-lime-silicate glass in the US and borosilicate in Japan
Uranium glass is glass which has had uranium, usually in oxide diuranate form, added to a glass mix before melting for colouration. The proportion usually varies from trace levels to about 2% uranium by weight, although some 20th-century pieces were made with up to 25% uranium.
The Tyndall effect is light scattering by particles in a colloid such as a very fine suspension. Also known as Tyndall scattering, it is similar to Rayleigh scattering, in that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength, so blue light is scattered much more strongly than red light. An example in everyday life is the blue colour sometimes seen in the smoke emitted by motorcycles, in particular two-stroke machines where the burnt engine oil provides these particles. The same effect can also be observed with tobacco smoke whose fine particles also preferentially scatter blue light.
An opacifier is a substance added to a material in order to make the ensuing system opaque. An example of a chemical opacifier is titanium dioxide (TiO2), which is used as an opacifier in paints, in paper, and in plastics. It has very high refraction index (rutile modification 2.7 and anatase modification 2.55) and optimum refraction is obtained with crystals about 225 nanometers. Impurities in the crystal alter the optical properties. It is also used to opacify ceramic glazes and milk glass; bone ash is also used.
Goldstone is a type of glittering glass made in a low-oxygen reducing atmosphere. The finished product can take a smooth polish and be carved into beads, figurines, or other artifacts suitable for semiprecious stone, and in fact goldstone is often mistaken for or misrepresented as a natural material.
Burmese glass is a type of opaque colored art glass, shading from yellow, blue or green to pink. It is found in either the rare original "shiny" finish or the more common "satin" finish. It is used for table glass and small, ornamental vases and dressing table articles.
Carnival glass is moulded or pressed glass to which an iridescent surface shimmer has been applied. It has previously been referred to as aurora glass, dope glass, rainbow glass, taffeta glass, and disparagingly as 'poor man's Tiffany'. The name Carnival glass was adopted by collectors in the 1950s as items of it were sometimes given as prizes at carnivals, fetes, and fairgrounds. However, evidence suggests that the vast majority of it was purchased by households to brighten homes at a time when only the well-off could afford bright electric lighting, as its finish catches the light even in dark corners. From the beginning of the 20th century, carnival glass was mass-produced around the world, but largely and initially in the U.S. It reached the height of its popularity in the 1920s, though it is still produced in small quantities today.
Depression glass is glassware made in the period 1929–1939, often clear or colored translucent machine-made glassware that was distributed free, or at low cost, in the United States and Canada around the time of the Great Depression. Depression glass is so called because collectors generally associate mass-produced glassware in pink, yellow, crystal, green, and blue with the Great Depression in America.
Venetian glass is glassware made in Venice, typically on the island of Murano near the city. Traditionally it is made with a soda–lime "metal" and is typically elaborately decorated, with various "hot" glass-forming techniques, as well as gilding, enamel, or engraving. Production has been concentrated on the Venetian island of Murano since the 13th century. Today Murano is known for its art glass, but it has a long history of innovations in glassmaking in addition to its artistic fame—and was Europe's major center for luxury glass from the High Middle Ages to the Italian Renaissance. During the 15th century, Murano glassmakers created cristallo—which was almost transparent and considered the finest glass in the world. Murano glassmakers also developed a white-colored glass that looked like porcelain. They later became Europe's finest makers of mirrors.
Dichroic glass is glass which can display multiple different colors depending on lighting conditions.
Sea glass are naturally weathered pieces of glass, which often have the appearance of tumbled stones. Sea glass is physically and chemically weathered glass found on beaches along bodies of salt water. These weathering processes produce natural frosted glass. Sea glass is used for decoration, most commonly in jewellery. "Beach glass" comes from fresh water and is often less frosted in appearance than sea glass. Sea glass takes 20–40 years, and sometimes as much as 100–200 years, to acquire its characteristic texture and shape. It is also colloquially referred to as drift glass from the longshore drift process that forms the smooth edges. In practice, the two terms are used interchangeably.
Opaline glass is a style of antique glassware that was produced in Europe, particularly 19th-century France. It was made by adding particular phosphates or oxides during the mixing process of the glass' processing, giving the material a quality of opalescence.
Mary Gregory was an American artist known for her decoration of glass products at the Boston and Sandwich Glass Company in Cape Cod, Massachusetts. Gregory worked for Boston and Sandwich from 1880 to 1884. Gregory painted lamps and plaques of landscape scenes during her years at B&SGC.
The A.H. Heisey Company was formed in Newark, Ohio, in 1895 by A.H. Heisey. The factory provided fine quality glass tableware and decorative glass figurines. Both pressed and blown glassware were made in a wide variety of patterns and colors. The company also made glass automobile headlights and Holophane Glassware lighting fixtures. The company was operated by Heisey and his sons until 1957, when the factory closed.
Glass coloring and color marking may be obtained in several ways.
The Macbeth-Evans Glass Company was an American glass company that created "almost every kind of glass for illuminating, industrial and scientific purposes," but is today famous for making depression glass.
Jadeite, “Jadite” or “Jade-ite” is a type of jade green opaque milk glass, originally popular in the United States in the early to mid-20th century. A blue milk glass called “Delphite” and "Azur-ite" was also produced for several years.
Pairpoint Glass Company is an American glass manufacturer based in Sagamore, Massachusetts. It is currently the oldest operating glass company in the United States.
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