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224:(η = 10 Poise) stresses relax within several hours. Stresses acquired at temperatures above the strain point, and not relaxed by annealing, remain in the glass indefinitely and may cause either short-term or much delayed failure. Stresses resulting from cooling too rapidly below the strain point largely are considered temporary, although they may be sufficient to cause short-term failure.
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by microscopic flow in response to the intense stresses they introduce internally. The piece then heat-soaks until its temperature is even throughout and the stress relaxation is adequate. The time necessary for this step varies depending on the type of glass and its maximum thickness. The glass then
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is a process of slowly cooling hot glass objects after they have been formed, to relieve residual internal stresses introduced during manufacture. Especially for smaller, simpler objects, annealing may be incidental to the process of manufacture, but in larger or more complex products it commonly
158:, which will indefinitely decrease the strength and reliability of the product. Inadequately annealed glass is likely to crack or shatter when subjected to relatively small temperature changes or to mechanical shock or stress. It even may fail spontaneously.
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of the glass. After annealing is complete the material can be cut to size, drilled, or polished without risk of its internal stresses shattering it.
176:(10 dyne-second/cm). For most kinds of glass, this annealing temperature is in the range of 454–482 °C (849–900 °F), and is the so-called
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197:(η = 10 Poise), below which even microscopic internal flow effectively stops and annealing stops with it. It then is safe to cool the product to
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154:. Annealing of glass is critical to its durability. Glass that has not been properly annealed retains thermal stresses caused by
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Werner Vogel: "Glass
Chemistry"; Springer-Verlag Berlin and Heidelberg GmbH & Co. K; 2nd revised edition (November 1994),
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E. F. Collins (1921) Electrically heated glass annealing lehr. Journal of the
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demands a special process of annealing in a temperature-controlled
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For other important temperatures in glass processing, see
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without breaking, but it is soft enough to relax internal
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161:To anneal glass, it is necessary to heat it to its
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27:Process for relieving stress in manufactured glass
794:Conservation and restoration of glass objects
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250:Fabrication and testing (optical components)
300:. Corning Museum of Glass. 9 December 2011.
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127:Learn how and when to remove this message
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65:adding citations to reliable sources
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864:Radioactive waste vitrification
819:Glass fiber reinforced concrete
52:needs additional citations for
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895:Glass engineering and science
731:Chemically strengthened glass
211:thermal expansion coefficient
564:Glass-ceramic-to-metal seals
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32:Annealing (disambiguation)
29:
595:Chemical vapor deposition
516:Ultra low expansion glass
406:Borophosphosilicate glass
201:at a rate limited by the
834:Glass-reinforced plastic
496:Sodium hexametaphosphate
726:Anti-reflective coating
600:Glass batch calculation
481:Photochromic lens glass
240:Annealing (metallurgy)
76:"Annealing" glass
859:Prince Rupert's drops
708:Transparent materials
668:Gradient-index optics
476:Phosphosilicate glass
824:Glass ionomer cement
698:Photosensitive glass
625:Liquidus temperature
446:Fluorosilicate glass
207:thermal conductivity
61:improve this article
30:For other uses, see
844:Glass-to-metal seal
766:Self-cleaning glass
688:Optical lens design
829:Glass microspheres
751:Hydrogen darkening
673:Hydrogen darkening
421:Chalcogenide glass
411:Borosilicate glass
910:Firing techniques
882:
881:
799:Glass-coated wire
771:sol–gel technique
756:Insulated glazing
693:Photochromic lens
678:Optical amplifier
630:sol–gel technique
294:"All About Glass"
180:-relief point or
172:, η, drops to 10
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16:(Redirected from
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620:Ion implantation
375:Glass transition
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78: –
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72:Find sources:
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50:This article
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39:
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19:
849:Porous glass
804:Safety glass
761:Porous glass
719:modification
589:
531:Wood's glass
451:Fused quartz
426:Cobalt glass
380:Supercooling
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298:www.cmog.org
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222:strain point
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195:strain point
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59:Please help
54:verification
51:
874:Glass fiber
839:Glass cloth
583:Preparation
559:CorningWare
441:Flint glass
436:Crown glass
389:Formulation
255:Float glass
186:deformation
165:temperature
150:known as a
905:Warm glass
889:Categories
869:Windshield
703:Refraction
663:Dispersion
471:Milk glass
466:Lead glass
271:References
265:Warm glass
163:annealing
87:newspapers
736:Corrosion
635:Viscosity
590:Annealing
170:viscosity
156:quenching
143:Annealing
117:July 2018
854:Pre-preg
658:Achromat
401:Bioglass
396:AgInSbTe
228:See also
785:Diverse
717:Surface
574:Zerodur
216:At the
190:strains
101:scholar
787:topics
650:Optics
456:GeSbTe
363:Basics
314:
209:, and
178:stress
103:
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569:Macor
536:ZBLAN
370:Glass
355:Glass
174:Poise
108:JSTOR
94:books
312:ISBN
152:lehr
148:kiln
80:news
63:by
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105:·
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