Murano glass (Italian: Murano vetro) objects produced on the island of Murano have a long trail of rich history that can be dated back to the thirteenth century. In addition to the peerless craftsmanship of glass masters shaping these masterpieces, another significant aspect that contributes to their beauty and quality is the raw materials that have undergone several changes since the Italian Murano glass, also known as Venetian glass, was first produced. In this post, we’ll dig into the raw materials used in the Murano glassmaking process nowadays.
These days, the mixture of raw materials to be supplied to the said batch melting process is composed of different substances, each of which has a precise function.
• Very pure silica sand: It brings in the glass silica (SiO2), the main component that measurably influences all the chemical and physical properties of a material.
• Must not contain impurities dyes.
• The iron oxide (Fe2O3) must be present in quantities less than 0.015%.
• Chromium oxide (Cr2O3) must be present in quantities less than 0.0003%.
• Grit is normally between 0.1 and 0.3 mm.
• Soda or sodium carbonate (Na2CO3)
• Potash or potassium carbonate (K2CO3)
• Lithium carbonate (LiCO3)
These raw materials of Italian Murano glass are synthetic products; they lower the melting temperature of the batch and extend the range of glass processing.
• Lime or calcium carbonate (CaCO3)
• Dolomite, or carbonate of calcium and magnesium (Ca, Mg (CO3))
• Barium carbonate (BaCO3)
• Zinc oxide (ZnO)
These raw materials lower the melting temperature of the glass batch, improve the chemical resistance of the glass and effectively shorten the interval processing.
• Sodium nitrate (NaNO3)
• Potassium nitrate (KNO3)
• Antimony oxide (Sb2O3)
• Sodium sulfate (Na2SO4)
The refining of raw materials has been in used since the nineteenth century, thanks to the higher temperature attained in the melting furnaces that allowed to perform the entire cycle of melting in one step. They facilitate the expulsion of gas from the molten glass.
• Potassium dichromate or chrome oxide is used to obtain green (emerald) colour in the Venetian glass.
• Cobalt oxide (CoO) is used for blue colour.
• Copper black oxide (CuO) is used for blue (aquamarine).
• Manganese dioxide (MnO2) is used to obtain purple (amethyst) in the Murano vetro.
• Gold is used for red (ruby).
• Selenium + cadmium sulfide is used for red.
• Sulfur + coal is used for yellow (amber).
• Cadmium sulfide is used for yellow.
• Cerium oxide + titanium oxide is used for lemon yellow.
• Erbium oxide is used for pink colour.
• Neodymium oxide is used for pinkish purple (alexandrite).
Raw Materials Used as Opacifiers
These are added to the batch in rather high quantities.
• Cryolite (Na3AlF6) + fluorspar (CaF2) is used to obtain opal Murano glass in white milk colour.
• Sodium sulfate (Na2SO4) + arsenious anhydride (As2O3) is used for opal silk.
• Minium (Pb3O4) + arsenious anhydride (As2O3) is used for opal sunflower.
• Minium (Pb3O4) + arsenious anhydride (As2O3) in high quantity is used for opal or enamel.
The aforesaid raw materials play a pivotal role in bringing various Murano or Venetian glass objects to the desired quality, shape and finish. If you wish to shop online for authentic Murano vetro items, then OriginalMuranoGlass.com is a trusted online store to visit for all your needs. It offers a large selection of Italian Murano glass such as sculptures, vases, jewellery, plates, glasses, chandeliers, table lamps and many more.