Editing Glass (section)

=== Colour ===
{{Main|Glass coloring and color marking}}

Colour in glass may be obtained by addition of homogenously distributed electrically charged ions (or [[Transparent materials#Absorption of light in solids|colour centres]]). While ordinary [[soda–lime glass]] appears colourless in thin section, [[iron(II) oxide]] (FeO) impurities produce a green tint in thick sections.<ref name="Mukherjee13">{{cite book|last=Mukherjee|first=Swapna|title=The Science of Clays: Applications in Industry, Engineering, and Environment|publisher=Springer Science & Business Media|year=2013|pages=142|url=https://books.google.com/books?id=wALFBAAAQBAJ&pg=PA142|isbn=978-9-4007-6683-9}}</ref> [[Manganese dioxide]] (MnO<sub>2</sub>), which gives glass a purple colour, may be added to remove the green tint given by FeO.<ref>{{Cite book|title=CRC Handbook of Metal Etchants|last1=Walker|first1=Perrin|last2=Tarn|first2=William H.|publisher=CRC press|year=1990|page=798|isbn=978-1-4398-2253-1|url=https://books.google.com/books?id=-2ObmTZTq2QC&pg=PA798}}</ref> FeO and [[chromium(III) oxide]] (Cr<sub>2</sub>O<sub>3</sub>) additives are used in the production of green bottles.<ref name="Mukherjee13" /> [[Iron (III) oxide]], on the other-hand, produces yellow or yellow-brown glass.<ref name="Langhamer03">{{cite book|url=https://books.google.com/books?id=UwLCa_h3hTEC&pg=PA273|title=The Legend of Bohemian Glass: A Thousand Years of Glassmaking in the Heart of Europe|first=Antonín|last=Langhamer|pages=273|year=2003|publisher=Tigris|isbn=978-8-0860-6211-2}}</ref> Low concentrations (0.025 to 0.1%) of [[cobalt oxide]] (CoO) produce rich, deep blue [[cobalt glass]].<ref>{{cite journal |title=3. Glass, Colour and the Source of Cobalt |url=https://intarch.ac.uk/journal/issue52/3/3.html |website=Internet Archaeology |doi=10.11141/ia.52.3}}</ref> [[Chromium]] is a very powerful colouring agent, yielding dark green.<ref>[http://www.speclab.com/elements/chromium.htm Chemical Fact Sheet – Chromium] {{Webarchive|url=https://web.archive.org/web/20170815033017/http://www.speclab.com/elements/chromium.htm |date=2017-08-15 }} www.speclab.com.</ref>
[[Sulphur]] combined with [[carbon]] and iron salts produces amber glass ranging from yellowish to almost black.<ref>David M Issitt. [https://web.archive.org/web/20070305020112/http://1st.glassman.com/articles/glasscolouring.html Substances Used in the Making of Coloured Glass] 1st.glassman.com.</ref> A glass melt can also acquire an amber colour from a reducing combustion atmosphere.<ref>{{Cite book|url=https://books.google.com/books?id=-mwoDwAAQBAJ&pg=PA211|title=Introduction to Glass Science and Technology|last=Shelby|first=James E.|year=2007|page=211|publisher=Royal Society of Chemistry|isbn=978-1-84755-116-0}}</ref> [[Cadmium sulfide]] produces imperial [[red]], and combined with selenium can produce shades of yellow, orange, and red.<ref name="Mukherjee13" /><ref name="Langhamer03" /> Addition of [[copper(II) oxide]] (CuO) produces a [[turquoise (color)|turquoise]] colour in glass, in contrast to [[copper(I) oxide]] (Cu<sub>2</sub>O) which gives a dull red-brown colour.<ref name="Nicholson00">{{cite book|url=https://books.google.com/books?id=Vj7A9jJrZP0C&pg=PA208|title=Ancient Egyptian Materials and Technology|first1=Paul T.|last1=Nicholson|first2=Ian|last2=Shaw|publisher=Cambridge University Press|year=2000|pages=208|isbn=978-0-521-45257-1}}</ref>

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* [[Nickel]], depending on the concentration, produces blue, or [[violet (colour)|violet]], or even [[black]] glass. [[Lead crystal]] with added nickel acquires purplish colour. Nickel together with a small amount of cobalt was used for decolourizing of [[lead glass]]. -->
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File:Bottle, wine (AM 1997.80.28-1).jpg|alt=A green glass bottle|[[Iron(II) oxide]] and [[chromium(III) oxide]] additives are often used in the production of green bottles.<ref name="Mukherjee13" />
File:Bristol.blue.glass.arp.750pix.jpg|alt=Several examples of deep blue glass|[[Cobalt oxide]] produces rich, [[cobalt glass|deep blue glass]], such as [[Bristol blue glass]].
File:Colour Eclipse, Danny Lane.jpg|alt=Three glass disks, with one coloured turquoise, another purple, and a third coloured red|Different oxide additives produce the different colours in glass: [[turquoise (color)|turquoise]] ([[copper(II) oxide]]),<ref name="Nicholson00" /> purple ([[manganese dioxide]]),<ref name="Mukherjee13" /> and red ([[cadmium sulfide]]).<ref name="Mukherjee13" />
File:Chinese snuff bottle, Qing dynasty, glass bottle with amber stopper, Honolulu Museum of Art.JPG|Red glass bottle with yellow glass overlay
File:Glass ornaments.JPG|Amber-coloured glass
File:Glass garland bowl MET DP122006.jpg|Four-colour Roman glass bowl, manufactured {{Circa|1st century B.C.}}
</gallery>