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Soda–lime glass
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<h2 id="production">Production</h2> <p>The manufacturing process for soda–lime glass consists in melting the <a href="/facts/Glass/hezRsAGf">raw materials</a>, which are the <a href="/facts/Silica/A3WILp6J">silica</a>, <a href="/facts/Sodium_oxide/QbdIGb8u">soda</a> (Na2O), <a href="/facts/Calcium_hydroxide/Kz2KzRd8">hydrated lime</a> (Ca(OH)2), <a href="/facts/Dolomite_(mineral)/tQfyK6AF">dolomite</a> (CaMg(CO3)2), which provides the magnesium oxide), and aluminium oxide; along with small quantities of <a href="/facts/Finery_forge/rL149zMT">fining</a> agents (e.g., <a href="/facts/Sodium_sulfate/KWzpxTmj">sodium sulfate</a> (Na2SO4), <a href="/facts/Sodium_chloride/MWcXl3Mb">sodium chloride</a> (NaCl), etc.) in a <a href="/facts/Glass_container_industry/aErFHSUC">glass furnace</a> at temperatures locally up to 1675 °C.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> The soda and the lime serve as a <a href="/facts/Flux_(metallurgy)/ruKFTPGD">flux</a> lowering the melting temperature of silica (1580 °C) as well as causing the mixture to soften as it heats, starting at as low as 700 °C. The temperature is only limited by the quality of the furnace structure material and by the glass composition. Relatively inexpensive minerals such as <a href="/facts/Trona/lnkhuQAW">trona</a>, <a href="/facts/Sand/MdTIt0M8">sand</a>, and <a href="/facts/Feldspar/DVvFnfA9">feldspar</a> are usually used instead of pure chemicals. Green and brown bottles are obtained from raw materials containing <a href="/facts/Iron_oxide/KDo8hLWn">iron oxide</a>. The mix of raw materials is termed <a href="/facts/Glass_container_industry/aErFHSUC">batch</a>. </p> <h2 id="applications">Applications</h2> <p>Soda–lime glass is divided technically into glass used for windows, called <a href="/facts/Flat_glass/6NUwUyBE">flat glass</a>, and glass for containers, called <a href="/facts/Container_glass/yQzFEh1g">container glass</a>. The two types differ in the application, production method (<a href="/facts/Float_glass/L10e3REc">float process</a> for windows, <a href="/facts/Glassblowing/dWf2rYAD">blowing and pressing</a> for containers), and chemical composition. Flat glass has a higher <a href="/facts/Magnesium_oxide/0GfLn47t">magnesium oxide</a> and <a href="/facts/Sodium_oxide/QbdIGb8u">sodium oxide</a> content than container glass, and a lower silica, <a href="/facts/Calcium_oxide/Wh9C8l7j">calcium oxide</a>, and <a href="/facts/Aluminium_oxide/wXM9P6pI">aluminium oxide</a> content.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> From the lower content of highly water-soluble ions (sodium and magnesium) in container glass comes its slightly higher <a href="/facts/Chemical_durability/lIC7H4we">chemical durability</a> against water, which is required especially for storage of beverages and food. </p> <h2 id="typical-compositions-and-properties">Typical compositions and properties</h2> <p>Soda–lime glass is relatively inexpensive, chemically stable, reasonably hard, and extremely workable. Because it can be resoftened and remelted numerous times, it is ideal for <a href="/facts/Glass_recycling/GsswICqG">glass recycling</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> It is used in preference to chemically-pure <a href="/facts/Silicon_dioxide/A3WILp6J">silica</a> (SiO2), otherwise known as <a href="/facts/Fused_quartz/avtX1fy3">fused quartz</a>. Whereas pure silica has excellent resistance to <a href="/facts/Thermal_shock/2vDgN5HQ">thermal shock</a>, being able to survive immersion in water while red hot, its high melting temperature (1723 <a href="/facts/Celsius/okAEu1CA">°C</a>) and viscosity make it difficult to work with.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Other substances are therefore added to simplify processing. One is the "soda", or <a href="/facts/Sodium_oxide/QbdIGb8u">sodium oxide</a> (Na2O), which is added in the form of sodium carbonate or related precursors. Soda lowers the glass-transition temperature. However, the soda makes the glass <a href="/facts/Sodium_silicate/055T0IYW">water-soluble</a>, which is usually undesirable. To provide for better chemical durability, the "<a href="/facts/Lime_(mineral)/uMcVXGBM">lime</a>" is also added. This is <a href="/facts/Calcium_oxide/Wh9C8l7j">calcium oxide</a> (CaO), generally obtained from <a href="/facts/Limestone/8ntvtFnR">limestone</a>. In addition, <a href="/facts/Magnesium_oxide/0GfLn47t">magnesium oxide</a> (MgO) and alumina, which is <a href="/facts/Aluminium_oxide/wXM9P6pI">aluminium oxide</a> (Al2O3), contribute to the durability. The resulting glass contains about 70 to 74% silica by weight. </p><p>Soda–lime glass undergoes a steady increase in <a href="/facts/Viscosity/QLVfrdCz">viscosity</a> with decreasing temperature, permitting operations of steadily increasing precision. The glass is readily formable into objects when it has a viscosity of 104 <a href="/facts/Poise_(unit)/NxFhk46h">poises</a>, typically reached at a temperature around 900 °C. The glass is softened and undergoes steady deformation when viscosity is less than 108 poises, near 700 °C. Though apparently hardened, soda–lime glass can nonetheless be annealed to remove internal stresses with about 15 minutes at 1014 poises, near 500 °C. The relationship between viscosity and temperature is largely logarithmic, with an <a href="/facts/Arrhenius_equation/TdAeo3Lf">Arrhenius equation</a> strongly dependent on the composition of the glass, but the activation energy increases at higher temperatures.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>The following table lists some physical properties of soda–lime glasses. Unless otherwise stated, the glass compositions and many experimentally determined properties are taken from one large study.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Those values marked in <i>italic</i> font have been interpolated from similar glass compositions (see <a href="/facts/Calculation_of_glass_properties/S8YzGwtw">calculation of glass properties</a>) due to the lack of experimental data. </p> <table><tbody><tr><th>Properties</th><th><a href="/facts/Container_glass/yQzFEh1g">Container glass</a></th><th><a href="/facts/Flat_glass/6NUwUyBE">Flat glass</a></th></tr><tr><td>Chemicalcomposition,wt%</td><td><table><tbody><tr><td>74</td><td><a href="/facts/Silicon_dioxide/A3WILp6J">SiO2</a></td><td>0.3</td><td><a href="/facts/Potassium_oxide/mmUVvPef">K2O</a></td></tr><tr><td>13</td><td><a href="/facts/Sodium_oxide/QbdIGb8u">Na2O</a></td><td>0.2</td><td><a href="/facts/Magnesium_oxide/0GfLn47t">MgO</a></td></tr><tr><td>10.5</td><td><a href="/facts/Calcium_oxide/Wh9C8l7j">CaO</a></td><td>0.04</td><td><a href="/facts/Iron(III)_oxide/vam0XoC5">Fe2O3</a></td></tr><tr><td>1.3</td><td><a href="/facts/Aluminium_oxide/wXM9P6pI">Al2O3</a></td><td>0.01</td><td><a href="/facts/Titanium_dioxide/T0KWmKcz">TiO2</a></td></tr><tr><td></td><td></td><td>0.2</td><td><a href="/facts/Sulfur_trioxide/Ijvm08Lq">SO3</a></td></tr></tbody></table></td><td><table><tbody><tr><td>73</td><td>SiO2</td><td>0.03</td><td>K2O</td></tr><tr><td>14</td><td>Na2O</td><td>4</td><td>MgO</td></tr><tr><td>9</td><td>CaO</td><td>0.1</td><td>Fe2O3</td></tr><tr><td>0.15</td><td>Al2O3</td><td>0.02</td><td>TiO2</td></tr><tr><td> </td><td></td><td></td><td></td></tr></tbody></table></td></tr><tr><td><a href="/facts/Viscosity/QLVfrdCz">Viscosity</a>log(η, dPa·s or poise) = <i>A</i> + <i>B</i> / (<i>T</i> in °C − <i>T</i>0)</td><td><table><tbody><tr><td>550 °C (1,022 °F)</td><td>1,450 °C (2,640 °F)</td></tr><tr><td><i>A</i></td></tr><tr><td><i>B</i></td><td>3922</td></tr><tr><td><i>T</i>0</td><td>291</td></tr></tbody></table></td><td><table><tbody><tr><td>550 °C (1,022 °F)</td><td>1,450 °C (2,640 °F)</td></tr><tr><td><i>A</i></td><td>−2.585</td></tr><tr><td><i>B</i></td><td>4215</td></tr><tr><td><i>T</i>0</td><td>263</td></tr></tbody></table></td></tr><tr><td><a href="/facts/Glass_transition_temperature/yVl3QzsT">Glass transition</a><a href="/facts/Glass_transition_temperature/yVl3QzsT">temperature</a>, Tg</td><td>573 °C (1,063 °F)</td><td>564 °C (1,047 °F)</td></tr><tr><td><a href="/facts/Coefficient_of_thermal_expansion/BP2vjX0N">Coefficient of</a><a href="/facts/Coefficient_of_thermal_expansion/BP2vjX0N">thermal expansion</a>,ppm/K, ~100–300 °C (212–572 °F)</td><td>9</td><td>9.5</td></tr><tr><td><a href="/facts/Density/92p6hh9I">Density</a>at 20 °C (68 °F), g/cm3</td><td>2.52</td><td>2.53</td></tr><tr><td><a href="/facts/Refractive_index/yjkzvgeE">Refractive index</a><i>n</i>D at 20 °C (68 °F)</td><td><i>1.518</i></td><td>1.520</td></tr><tr><td><a href="/facts/Dispersion_(optics)/cUdHnYXz">Dispersion</a> at 20 °C (68 °F),104 × (<i>n</i>F − <i>n</i>C)</td><td><i>86.7</i></td><td><i>87.7</i></td></tr><tr><td><a href="/facts/Young%2527s_modulus/MV5JMCIM">Young's modulus</a>at 20 °C (68 °F), GPa</td><td><i>72</i></td><td><i>74</i></td></tr><tr><td><a href="/facts/Shear_modulus/9e9IvJnz">Shear modulus</a>at 20 °C (68 °F), GPa</td><td><i>29.8</i></td><td><i>29.8</i></td></tr><tr><td><a href="/facts/Liquidus_temperature/RtXE2d8B">Liquidus</a><a href="/facts/Liquidus_temperature/RtXE2d8B">temperature</a></td><td><i>1,040 °C (1,900 °F)</i></td><td><i>1,000 °C (1,830 °F)</i></td></tr><tr><td><a href="/facts/Heat_capacity/I63nzSyp">Heat</a><a href="/facts/Heat_capacity/I63nzSyp">capacity</a> at 20 °C (68 °F),J/(mol·K)</td><td><i>49</i></td><td><i>48</i></td></tr><tr><td><a href="/facts/Surface_tension/EuluYmSM">Surface tension</a>,at ~1,300 °C (2,370 °F), mJ/m2</td><td>315</td><td></td></tr><tr><td><a href="/facts/Chemical_durability/lIC7H4we">Chemical durability</a>,<a href="/facts/Corrosion/lIC7H4we">Hydrolytic class</a>,after ISO 719<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></td><td><i>3</i></td><td><i>3...4</i></td></tr><tr><td><a href="/facts/Stress_intensity_factor/pLrUo683">Critical stress</a><a href="/facts/Stress_intensity_factor/pLrUo683">intensity factor</a>,<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a>(KIC), MPa.m0.5</td><td><i>?</i></td><td><i>0.75</i></td></tr></tbody></table> <ul><li><a href="/facts/Coefficient_of_restitution/K1vlBw4B">Coefficient of restitution</a> (glass sphere vs. glass wall): 0.97 ± 0.01<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></li> <li><a href="/facts/Thermal_conductivity/qWnSG3nQ">Thermal conductivity</a>: 0.7–1.3 W/(m·K)<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a></li> <li><a href="/facts/Mohs_scale_of_mineral_hardness/wXBMcVIm">Hardness (Mohs scale)</a>: 6<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a></li> <li><a href="/facts/Knoop_hardness_test/PPc2xzny">Knoop hardness</a>: 585 kg/mm2 + 20</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Glass_batch_calculation/zUpksLHg">Glass batch calculation</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Estes, Adam Clark (March 16, 2019). "The Pyrex Glass Controversy That Just Won't Die". Gizmodo. Retrieved 2019-03-22. <a href="https://gizmodo.com/the-pyrex-glass-controversy-that-just-wont-die-1833040962" target="_blank">https://gizmodo.com/the-pyrex-glass-controversy-that-just-wont-die-1833040962</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Borosilicate Glass vs. Soda Lime Glass? - Rayotek News". rayotek.com. Archived from the original on 23 April 2017. Retrieved 23 April 2017. <a href="https://rayotek.com/wpnews/borosilicate-glass-vs-soda-lime-glass/" target="_blank">https://rayotek.com/wpnews/borosilicate-glass-vs-soda-lime-glass/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Robertson, Gordon L. (22 September 2005). Food Packaging: Principles and Practice (Second ed.). CRC Press. ISBN 978-0-8493-3775-8. Archived from the original on 2 December 2017. <a href="978-0-8493-3775-8" target="_blank">978-0-8493-3775-8</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>B. H. W. S. de Jong, "Glass"; in "Ullmann's Encyclopedia of Industrial Chemistry"; 5th edition, vol. A12, VCH Publishers, Weinheim, Germany, 1989, ISBN 978-3-527-20112-9, pp. 365–432. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"High temperature glass melt property database for process modeling"; Eds.: Thomas P. Seward III and Terese Vascott; The American Ceramic Society, Westerville, Ohio, 2005, ISBN 1-57498-225-7 <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>"Calcium Carbonate - Glass Manufacturing". congcal.com. congcal. 28 June 2012. Retrieved 5 August 2013. <a href="http://www.congcal.com/markets/glass/" target="_blank">http://www.congcal.com/markets/glass/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Gerace, Katy S.; Mauro, John C. (2024). "Characterization of soda–lime silicate glass bottles to support recycling efforts". International Journal of Ceramic Engineering & Science. 6 (3): e10217. doi:10.1002/ces2.10217. <a href="https://doi.org/10.1002%2Fces2.10217" target="_blank">https://doi.org/10.1002%2Fces2.10217</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Thomas H. Sanders Jr. "Viscosity Behavior of Oxide Glasses". Coursera. <a href="https://www.coursera.org/learn/material-behavior/lecture/IIkka/6-5-viscosity-behavior-of-oxide-glasses" target="_blank">https://www.coursera.org/learn/material-behavior/lecture/IIkka/6-5-viscosity-behavior-of-oxide-glasses</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"High temperature glass melt property database for process modeling"; Eds.: Thomas P. Seward III and Terese Vascott; The American Ceramic Society, Westerville, Ohio, 2005, ISBN 1-57498-225-7 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"ISO 719:1985 - Glass -- Hydrolytic resistance of glass grains at 98 degrees C -- Method of test and classification". iso.org. <a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=4948" target="_blank">http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=4948</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Wiederhorn, S.M. (1969). "Fracture stress energy of glass". Journal of the American Ceramic Society. 52 (2): 99–105. doi:10.1111/j.1151-2916.1969.tb13350.x. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Gondret, P.; M. Lance; L. Petit (2002). "Bouncing Motion of Spherical Particles in Fluids". Physics of Fluids. 14 (2): 643–652. doi:10.1063/1.1427920. <a href="http://pof.aip.org/resource/1/phfle6/v14/i2/p643_s1" target="_blank">http://pof.aip.org/resource/1/phfle6/v14/i2/p643_s1</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Janssen, L. P. B. M., Warmoeskerken, M. M. C. G., 2006. Transport phenomena data companion. Delft: VVSD. <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"Soda-Lime (Float) Glass Material Properties :: MakeItFrom.com". makeitfrom.com. <a href="http://www.makeitfrom.com/data/?material=Soda_Lime_Glass" target="_blank">http://www.makeitfrom.com/data/?material=Soda_Lime_Glass</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> </ol>