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Glass coloring and color marking
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<h2 id="coloring-ions">Coloring ions</h2> <p>Ordinary <a href="/facts/Soda-lime_glass/CFYbacLU">soda-lime glass</a> appears <a href="/facts/Color/XDvW7ESP">colorless</a> to the naked eye when it is thin, although iron oxide impurities produce a <a href="/facts/Green/gFTac7St">green</a> tint which can be viewed in thick pieces or with the aid of scientific instruments. Further <a href="/facts/Metal/PT8hNX6R">metals</a> and metal <a href="/facts/Oxide/DXtoVe1C">oxides</a> can be added to glass during its manufacture to change its color which can enhance its aesthetic appeal. Examples of these additives are listed below: </p> <ul><li><a href="/facts/Iron(II)_oxide/H9V7S3MG">Iron(II) oxide</a> may be added to glass resulting in bluish-green glass which is frequently used in beer bottles. Together with <a href="/facts/Chromium/6sVk6Uu7">chromium</a> it gives a richer green color, used for <a href="/facts/Wine_bottle/pXWQb5S6">wine bottles</a>.</li> <li><a href="/facts/Sulfur/IK0amTfM">Sulfur</a>, together with <a href="/facts/Carbon/ukrgQexo">carbon</a> and iron salts, is used to form iron polysulfides and produce amber glass ranging from yellowish to almost black. In <a href="/facts/Borosilicate_glass/Ywaqt7Ic">borosilicate glasses</a> rich in boron, sulfur imparts a blue color. With <a href="/facts/Calcium/hf252CC0">calcium</a> it yields a deep yellow color.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li> <li><a href="/facts/Manganese/j9ELd1TL">Manganese</a> can be added in small amounts to remove the <a href="/facts/Green/gFTac7St">green</a> tint given by iron, or in higher concentrations to give glass an <a href="/facts/Amethyst_(color)/FwCJAXYP">amethyst</a> color. Manganese is one of the oldest glass additives, and purple manganese glass was used since early Egyptian history.</li> <li><a href="/facts/Manganese_dioxide/HRwgXlUe">Manganese dioxide</a>, which is <a href="/facts/Black/Sl9vnhcG">black</a>, is used to remove the green color from the glass; in a very slow process this is converted to <a href="/facts/Sodium_permanganate/hGuXQC8T">sodium permanganate</a>, a dark <a href="/facts/Purple/PVL40QPo">purple</a> compound. In <a href="/facts/New_England/ufw2BmSl">New England</a> some houses built more than 300 years ago have window glass which is lightly tinted <a href="/facts/Violet_(color)/zcNJGApt">violet</a> because of this chemical change, and such glass panes are prized as antiques. This process is widely confused with the formation of "desert amethyst glass", in which glass exposed to desert sunshine with a high ultraviolet component develops a delicate violet tint. Details of the process and the composition of the glass vary and so do the results, because it is not a simple matter to obtain or produce properly controlled specimens.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li> <li>Small concentrations of <a href="/facts/Cobalt/gqhScEw4">cobalt</a> (0.025 to 0.1%) yield <a href="/facts/Blue/DHWb8MUa">blue</a> glass. The best results are achieved when using glass containing <a href="/facts/Potash/4e2vBL9L">potash</a>. Very small amounts can be used for decolorizing.</li> <li>2 to 3% of <a href="/facts/Copper(II)_oxide/62mUJlpm">copper oxide</a> produces a <a href="/facts/Turquoise_(color)/olC5xCzv">turquoise</a> color.</li> <li><a href="/facts/Nickel/KwMCHYRP">Nickel</a>, depending on the concentration, produces blue, or <a href="/facts/Violet_(colour)/zcNJGApt">violet</a>, or even <a href="/facts/Black/Sl9vnhcG">black</a> glass. <a href="/facts/Lead_crystal/FtgPe6r2">Lead crystal</a> with added nickel acquires purplish color. Nickel together with a small amount of cobalt was used for decolorizing of <a href="/facts/Lead_glass/FtgPe6r2">lead glass</a>.</li> <li><a href="/facts/Chromium/6sVk6Uu7">Chromium</a> is a very powerful colorizing agent, yielding dark green<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> or in higher concentrations even black color. Together with tin oxide and arsenic it yields <a href="/facts/Emerald_(color)/tj1IJvbu">emerald green</a> glass. Chromium <a href="/facts/Aventurine/edxX8SV2">aventurine</a>, in which <a href="/facts/Aventurescence/QN9apf4N">aventurescence</a> is achieved by growth of large parallel <a href="/facts/Chromium(III)_oxide/5C6XdjrQ">chromium(III) oxide</a> plates during cooling, is made from glass with added chromium oxide in amount above its solubility limit in glass.</li> <li><a href="/facts/Cadmium/wXkV2eIX">Cadmium</a> together with sulphur forms <a href="/facts/Cadmium_sulfide/lsYV3Gum">cadmium sulfide</a> and results in deep yellow color, often used in glazes. However, cadmium is toxic. Together with selenium and sulphur it yields shades of bright red and orange.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></li> <li>Adding <a href="/facts/Titanium/53ArnDoy">titanium</a> produces <a href="/facts/Yellow/KrLNgk4v">yellowish</a>-<a href="/facts/Brown/QQNvjboh">brown</a> glass. Titanium, rarely used on its own, is more often employed to intensify and brighten other colorizing additives.</li> <li><a href="/facts/Uranium/n2sGWBzU">Uranium</a> (0.1 to 2%) can be added to give glass a fluorescent yellow or <a href="/facts/Green/gFTac7St">green</a> color.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> <a href="/facts/Uranium_glass/FbhSol8q">Uranium glass</a> is typically not <a href="/facts/Radioactive_decay/Ya6FVjt4">radioactive</a> enough to be dangerous, but if ground into a powder, such as by polishing with sandpaper, and inhaled, it can be <a href="/facts/Carcinogenic/soH8Y9CE">carcinogenic</a>. When used with lead glass with very high proportion of lead, produces a deep red color.</li> <li><a href="/facts/Didymium/qrefFWn8">Didymium</a> gives green color (used in UV filters) or lilac red.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a></li></ul> <h2 id="striking-glasses">Striking glasses</h2> <ul><li><a href="/facts/Selenium/k975NApC">Selenium</a>, like manganese, can be used in small concentrations to decolorize glass, or in higher concentrations to impart a <a href="/facts/Red/gLnFAVx4">reddish</a> color, caused by selenium <a href="/facts/Nanoparticle/k8kNxX4E">nanoparticles</a> dispersed in glass. It is a very important agent to make pink and red glass. When used together with <a href="/facts/Cadmium_sulfide/lsYV3Gum">cadmium sulfide</a>,<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> it yields a brilliant red color known as "Selenium Ruby".</li> <li>Pure metallic <a href="/facts/Copper/I8PEE8oX">copper</a> produces a very dark red, opaque glass, which is sometimes used as a substitute for gold in the production of <a href="/facts/Ruby_(color)/N2gYNwCc">ruby</a>-colored glass.</li> <li>Metallic <a href="/facts/Gold/1znknojp">gold</a>, in very small concentrations (around 0.001%, or 10 ppm), produces a rich ruby-colored glass ("Ruby Gold" or "Rubino Oro"), while lower concentrations produces a less intense red, often <a href="/facts/Marketing/LttVQ66t">marketed</a> as "<a href="/facts/Cranberry_glass/n7qmIHlT">cranberry</a>". The color is caused by the size and dispersion of gold particles. Ruby gold glass is usually made of <a href="/facts/Lead_glass/FtgPe6r2">lead glass</a> with added <a href="/facts/Tin/obW9mqc3">tin</a>.</li> <li><a href="/facts/Silver/xXe41BGg">Silver</a> compounds such as <a href="/facts/Silver_nitrate/U5w4A3DN">silver nitrate</a> and <a href="/facts/Silver_halide/uM8V4wJc">silver halides</a> can produce a range of colors from <a href="/facts/Orange_(colour)/FNScAQvv">orange</a>-red to yellow. The way the glass is heated and cooled can significantly affect the colors produced by these compounds. Also <a href="/facts/Photochromic_lens/BVuhsBqK">photochromic lenses</a> and <a href="/facts/Photosensitive_glass/9ysK2nrv">photosensitive glass</a> are based on silver.</li> <li><a href="/facts/Purple_of_Cassius/WcUnVRwo">Purple of Cassius</a> is a purple pigment formed by the reaction of gold salts with tin(II) chloride.</li></ul> <h2 id="coloring-added-to-glass">Coloring added to glass</h2> <p>The principal methods of this are <a href="/facts/Enamelled_glass/cqQGWavA">enamelled glass</a>, essentially a technique for painting patterns or images, used for both glass vessels and on stained glass, and glass paint, typically in black, and <a href="/facts/Stained_glass/oUCut2Mc">silver stain</a>, giving yellows to oranges on stained glass. All of these are fired in a kiln or furnace to fix them, and can be extremely durable when properly applied. This is not true of "cold-painted" glass, using oil paint or other mixtures, which rarely last more than a few centuries. </p> <h2 id="colored-inclusions">Colored inclusions</h2> <p><a href="/facts/Tin_oxide/mSgEwsFv">Tin oxide</a> with <a href="/facts/Antimony_trioxide/b3LraQvL">antimony</a> and <a href="/facts/Arsenic_trioxide/YhlrDAg7">arsenic</a> oxides produce an opaque <a href="/facts/White/L2qjm4G0">white</a> glass (<a href="/facts/Milk_glass/ayGtH8p3">milk glass</a>), first used in <a href="/facts/Venice/Xzc2uVDg">Venice</a> to produce an imitation <a href="/facts/Porcelain/deuLm3sb">porcelain</a>, very often then <a href="/facts/Enamelled_glass/cqQGWavA">painted with enamels</a>. Similarly, some <a href="/facts/Smoked_glass/tccfz54B">smoked glasses</a> may be based on dark-colored inclusions, but with ionic coloring it is also possible to produce dark colors (see above). </p> <h2 id="color-caused-by-scattering">Color caused by scattering</h2> <p>Glass containing two or more <a href="/facts/Phase_(matter)/NkHXDdN3">phases</a> with different <a href="/facts/Refractive_index/yjkzvgeE">refractive indices</a> shows coloring based on the <a href="/facts/Tyndall_effect/QJ9I8yeI">Tyndall effect</a> and explained by the <a href="/facts/Mie_theory/5mJc3SrT">Mie theory</a>, if the dimensions of the phases are similar or larger than the <a href="/facts/Frequency/QUSbPaW8">wavelength of visible light</a>. The scattered light is blue and violet as seen in the image, while the transmitted light is yellow and red. </p> <h2 id="dichroic-glass">Dichroic glass</h2> <p class="note">Main article: <a href="/facts/Dichroic_glass/Ey6Y5G7X">Dichroic glass</a></p> <p>Dichroic glass has one or several coatings in the nanometer-range (for example metals, metal oxides, or nitrides) which give the glass <a href="/facts/Dichroic/BvgNMAyz">dichroic</a> optical properties. Also the blue appearance of some automobile <a href="/facts/Windshield/BffeD1Q7">windshields</a> is caused by dichroism. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Crystal_field_theory/yTECtz0r">Crystal field theory</a> - physical explanation coloring</li> <li><a href="/facts/Medieval_stained_glass/pAnIc1lT">Color of medieval stained glass</a></li> <li><a href="/facts/Hydrogen_darkening/T7HYg65c">Hydrogen darkening</a></li> <li><a href="/facts/Hydroxyl_ion_absorption/sQetkom5">Hydroxyl ion absorption</a></li> <li><a href="/facts/Transparent_materials/PRryNNW6">Transparent materials</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Bernard H. W. S. De Jong, Ruud G. C. Beerkens, Peter A. van Nijnatten: "Glass", in: "Ullmann's Encyclopedia of Industrial Chemistry"; Wiley-VCH Verlag GmbH & Co. KGaA, 2002, doi:10.1002/14356007.a12_365 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Werner Vogel: "Glass Chemistry"; Springer-Verlag Berlin and Heidelberg GmbH & Co. K; 2nd revised edition (November 1994), ISBN 3-540-57572-3 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Bernard H. W. S. De Jong, Ruud G. C. Beerkens, Peter A. van Nijnatten: "Glass", in: "Ullmann's Encyclopedia of Industrial Chemistry"; Wiley-VCH Verlag GmbH & Co. KGaA, 2002, doi:10.1002/14356007.a12_365 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Formation of Gold Nanoparticles in Gold Ruby Glass: The influence of Tin <a href="https://www.physik.tu-muenchen.de/archaeometry/download/ICAMERuby.pdf" target="_blank">https://www.physik.tu-muenchen.de/archaeometry/download/ICAMERuby.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Werner Vogel: "Glass Chemistry"; Springer-Verlag Berlin and Heidelberg GmbH & Co. K; 2nd revised edition (November 1994), ISBN 3-540-57572-3 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Werner Vogel: "Glass Chemistry"; Springer-Verlag Berlin and Heidelberg GmbH & Co. K; 2nd revised edition (November 1994), ISBN 3-540-57572-3 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Substances Used in the Making of Coloured Glass Archived 2010-04-02 at the Wayback Machine 1st-glass.1st-things.com (David M Issitt). Retrieved 9 April 2014 <a href="http://1st-glass.1st-things.com/articles/glasscolouring.html" target="_blank">http://1st-glass.1st-things.com/articles/glasscolouring.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Nassau, Kurt (2001). The physics and chemistry of color: the fifteen causes of color. Wiley. ISBN 978-0-471-39106-7. Retrieved 4 April 2013. <a href="978-0-471-39106-7" target="_blank">978-0-471-39106-7</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Chemical Fact Sheet - Chromium Archived 2017-08-15 at the Wayback Machine www.speclab.com. Retrieved 3 August 2006 <a href="http://www.speclab.com/elements/chromium.htm" target="_blank">http://www.speclab.com/elements/chromium.htm</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>R. Barbour. "Glassblowing for Laboratory Technicians" (PDF). wiredfreak.com. Archived from the original (PDF) on 26 March 2012. Retrieved 9 April 2014. <a href="https://web.archive.org/web/20120326025412/http://wiredfreak.com/.Chemistry%20eBooks%20Collection/Laboratory/Glassblowing/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour.pdf" target="_blank">https://web.archive.org/web/20120326025412/http://wiredfreak.com/.Chemistry%20eBooks%20Collection/Laboratory/Glassblowing/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour.pdf</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Uranium Glass www.glassassociation.org.uk (Barrie Skelcher). Retrieved 3 August 2006 <a href="http://www.glassassociation.org.uk/sites/default/files/WEBSITE%20Uranium%20Glass%20website%20%282%29.pdf" target="_blank">http://www.glassassociation.org.uk/sites/default/files/WEBSITE%20Uranium%20Glass%20website%20%282%29.pdf</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>R. Barbour. "Glassblowing for Laboratory Technicians" (PDF). wiredfreak.com. Archived from the original (PDF) on 26 March 2012. Retrieved 9 April 2014. <a href="https://web.archive.org/web/20120326025412/http://wiredfreak.com/.Chemistry%20eBooks%20Collection/Laboratory/Glassblowing/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour.pdf" target="_blank">https://web.archive.org/web/20120326025412/http://wiredfreak.com/.Chemistry%20eBooks%20Collection/Laboratory/Glassblowing/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour/Glassblowing%20for%20laboratory%20technicians%20-%20Barbour.pdf</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Selenium". Illustrated Glass Dictionary. www.glassonline.com. Archived from the original on 1 October 2011. Retrieved 9 April 2014. <a href="https://web.archive.org/web/20111001052915/http://www.glassonline.com/infoserv/dictionary/355.html" target="_blank">https://web.archive.org/web/20111001052915/http://www.glassonline.com/infoserv/dictionary/355.html</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> </ol>