Milk glass is an opaque or translucent, milk white or colored

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

that can be blown or pressed into a wide variety of shapes. First made in

Venice Venice ( ; ; , formerly ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 islands that are separated by expanses of open water and by canals; portions of the city are li ...

in the 16th century, colors include blue, pink, yellow, brown, black, and white.

Principle

Milk glass contains dispersion particles with a

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

significantly different from the glass matrix which scatters light by the

Tyndall scattering The Tyndall effect is light scattering by particles in a colloid such as a very fine suspension (a sol). Also known as Tyndall scattering, it is similar to Rayleigh scattering, in that the intensity of the scattered light is inversely proport ...

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

opacifier 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 refract ...

s 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 Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water. The exact composition of these compounds varies depending upon the type of bon ...

tin dioxide Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names, this oxide of tin is an important material in ti ...

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

, and

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

compounds. These are also added to

ceramic glaze Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimize the adherence of pollutants. Glazing renders earthenware impermeable to water, sealing th ...

s which, chemically; be considered a specific kind of milk glass.

History

Milk glass was first made in

in the 16th century (''lattimo'') as a translucent competitor for

porcelain Porcelain (), also called china, is a ceramic material made by heating Industrial mineral, raw materials, generally including kaolinite, in a kiln to temperatures between . The greater strength and translucence of porcelain, relative to oth ...

. 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. Made into decorative

dinnerware Tableware items are the dishware and utensils used for setting a table, serving food, and dining. The term includes cutlery, glassware, serving dishes, serving utensils, and other items used for practical as well as decorative purposes. The q ...

, lamps,

vase A vase ( or ) is an open container. It can be made from a number of materials, such as ceramics, glass, non- rusting metals, such as aluminium, brass, bronze, or stainless steel. Even wood has been used to make vases, either by using tree specie ...

s, and costume jewellery, milk glass was highly popular during the ''

fin de siècle "''Fin de siècle''" () is a French term meaning , a phrase which typically encompasses both the meaning of the similar English idiom '' turn of the century'' and also makes reference to the closing of one era and onset of another. Without co ...

''. Pieces made for the wealthy of the

Gilded Age In History of the United States, United States history, the Gilded Age is the period from about the late 1870s to the late 1890s, which occurred between the Reconstruction era and the Progressive Era. It was named by 1920s historians after Mar ...

are known for their strikingly delicate beauty in both color and design while

Depression glass Depression glass is glassware made in the period 1929–1939, often clear or colored Transparency and translucency, translucent machine-made glassware that was distributed free, or at low cost, in the United States and Canada around the time of ...

pieces of the 1930s and 1940s are less so. USA-NYC-Grand Central Terminal Clock

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 The Chicago Theatre, originally known as the Balaban and Katz Chicago Theatre, is a landmark Theater (structure), theater located on North State Street (Chicago), State Street in the Loop, Chicago, Loop area of Chicago, Illinois. Built in 19 ...

has been donated to the

Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums, Education center, education and Research institute, research centers, created by the Federal government of the United States, U.S. government "for the increase a ...

. A famous use of milk glass is for the four faces of the information booth clock at

Grand Central Terminal Grand Central Terminal (GCT; also referred to as Grand Central Station or simply as Grand Central) is a commuter rail terminal station, terminal located at 42nd Street (Manhattan), 42nd Street and Park Avenue in Midtown Manhattan, New York Ci ...

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

Barbetta Barbetta is an Italian restaurant focused on Piemonte cuisine located at 321 West 46th Street (between 8th Avenue and 9th Avenue) on the Theater District's Restaurant Row in New York City. Founded in 1906, Barbetta is one of the city's oldest fa ...

, the New York Italian restaurant founded in 1906 and still in business as of 2022, has what is said to be the last opal glass sign in the city.

Collectible

Milk glass has a considerable following of collectors. Glass makers continue to produce both original pieces and reproductions of popular collectible pieces and patterns.

Notable U.S. manufacturers

* Dithridge & Company *

Fenton Glass Company The Fenton Art Glass Company is a glass manufacturer founded in 1905 by brothers Frank L. Fenton and John W. Fenton. History The original factory was in an old glass factory in Martins Ferry, Ohio, in 1905. The factory at one time was owned by th ...

Fostoria Glass Company The Fostoria Glass Company was a manufacturer of pressed, blown and hand-molded glassware and tableware. It began operations in Fostoria, Ohio, on December 15, 1887, on land donated by the townspeople. The new company was formed by men from West ...

Imperial Glass Company The Imperial Glass Company is located in Bellaire, Ohio Ohio ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Erie to the north, Pennsylvania to the east, West Virginia ...

* Kanawha Glass Co. * L.E. Smith Glass Company *

Mosser Glass Mosser Glass is a company making handmade glass, founded in Cambridge, Ohio Cambridge ( ) is a city in Guernsey County, Ohio, United States, and its county seat. The population was 10,089 at the 2020 census. It lies in the Appalachian Plateau ...

* Thai Soojung Glass Company LimitedThai Soojung Glass Company Limited
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Westmoreland Glass Company The Westmoreland Glass Company was a company that produced glass in Grapeville, Pennsylvania. History The Westmoreland Glass Company was founded in 1889 when a group of men purchased the Specialty Glass Company located in East Liverpool, Ohio, an ...

References

External links