In Short: Lattimo or Milk Glass glass-making technique used to create milky-white opaque glass was known in Ancient Roman times, and after a period of dark ages as Venetian Empire was getting stronger, the baton of Roman glass craftsmanship passed to Venice. Through experimentation and tireless work the recipe for Lattimo glass was obtained by Murano master glass-makers in the fourteenth century.
At first milk glass melted at comparatively low temperatures of between 700 and 900 degrees Celsius was used for enamel decorations on gold and silver in goldsmith workshops, who purchased it from the glass artisans. Later on, Lattimo became very popular because it was a wonderful imitation of the look of Chinese porcelain, a coveted imported good that no-one in Europe could make. Before Europeans learned to make their own porcelain in the eighteenth century, richly decorated milky Murano Glass looking like porcelain was all the rage in European dining rooms and salons for nearly three centuries.
So popular was Lattimo glass, that despite tough laws existing on Murano around glass-making trade secrets, the production of this milky-white glass spread beyond Murano and happened also in Bohemia, France, Germany, Spain, and England. Often this glassware was decorated with elaborate colored or polychrome enamel and gold pictures portraying mythological and biblical subjects, pastoral scenes, flowers, animals, birds, geometrical designs, and coats of arms. For centuries Lattimo plates, sugar bowls, bottles, cups, and various decorative objects graced the dinner services of the wealthy in Venice and beyond.
In order to create Lattimo glass a number of ingredients were used, each for its own purpose. The key ones were the crystal amalgam, which was basically an impure vitreous paste, manganese oxide for bleaching, and tin oxide for clouding the transparent glass to create the matte effect. Later on the production process was enhanced and instead of the tin oxide lead arsenic was used for matting. In modern Lattimo glass the matting agent is calcium fluoride in tiny particles.
Milk Glass also opened a new era in Murano Glass production, when it became possible to attribute glassware to particular workshops. As Lattimo glass was in such high demand, the artisans attempted to overtake each other in workmanship, decoration, and details. Two leading family workshops ultimately emerged in the eighteenth century: Miotti and Bertolini. Bertolini family name enjoyed prominence on Murano, as they were listed in Murano's Golden Book of noble citizens and owned a majolica factory on the island, and they managed to obtain an exclusive right to produce all sorts of Lattimo glass, including transparent, opaque, with and without decoration and gold leaf, for 20 years.
Afterwards as the exclusivity expired, Miotti and many other glassworks made fine Lattimo glass, many marking their pieces with specific symbols or emblems signifying their brand. The abundance of Venetian Lattimo glass all over Europe for several centuries allowed many pieces to survive to our days, and today one can see Murano Glass Lattimo in virtually all important glass collections around the world.