Editing Bulletproof glass (section)

==Construction==
[[File:Bulletproof_glass_visualisation.png|thumb|A rough visualisation of bulletproof glass, composed of layers of plastic sheeting (grey) and layers of glass (blue)]]
Bullet-resistant glass is constructed using layers of [[laminated glass]]. The more layers there are, the more protection the glass offers. When a weight reduction is needed, [[polycarbonate]] (a [[thermoplastic]]) is laminated onto the safe side to stop [[spall]]. The aim is to make a material with the appearance and clarity of standard glass but with effective protection from small arms. Polycarbonate designs usually consist of products such as Armormax, Makroclear, Cyrolon: a soft coating that heals after being scratched (such as elastomeric carbon-based polymers) or a hard coating that prevents scratching (such as silicon-based polymers).<ref name="effect of temperature">{{cite journal| author1=Walley, S.M.| author2=Field J.E.| author3=Blair, P.W.| author4=Milford, A.J.| title=The effect of temperature on the impact behaviour of glass/polycarbonate laminates.| journal=International Journal of Impact Engineering| publisher=Elsevier Science Ltd| url=http://www.smf.phy.cam.ac.uk/Publications/Strength%20papers/574StrWalleyIJIE30.pdf| issue=30?| pages=31–52| date=March 11, 2003| volume=30| format=pdf-1.17 Mb| access-date=September 15, 2013| doi=10.1016/S0734-743X(03)00046-0}}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

The plastic in laminate designs also provides resistance to impact from physical assault from blunt and sharp objects. The plastic provides little in the way of bullet-resistance. The glass, which is much harder than plastic, flattens the bullet, and the plastic deforms, with the aim of absorbing the rest of the energy and preventing penetration. The ability of the polycarbonate layer to stop projectiles with varying energy is directly proportional to its thickness,<ref name=Deformation>{{cite web| author=Gunnarsson CA| title=Deformation and Failure of Polycarbonate during Impact as a Function of Thickness.| url=http://sem-proceedings.com/09s/sem.org-SEM-2009-Ann-Conf-s068p04-Deformation-Failure-Polycarbonate-During-Impact-as-Function.pdf| work=Proceedings of the Society for Experimental Mechanics (SEM) Annual Conference, June 1–4, 2009, Albuquerque New Mexico, USA| publisher=Society for Experimental Mechanics Inc| date=June 2009| format=pdf-443Kb| access-date=September 15, 2013| display-authors=etal| archive-url=https://web.archive.org/web/20131004214030/http://sem-proceedings.com/09s/sem.org-SEM-2009-Ann-Conf-s068p04-Deformation-Failure-Polycarbonate-During-Impact-as-Function.pdf| archive-date=2013-10-04| url-status=dead}}</ref> and bulletproof glass of this design may be up to 3.5 inches thick.<ref name="usarmorllc1"/>

Laminated glass layers are built from glass sheets bonded together with polyvinyl butyral, polyurethane, Sentryglas, or ethylene-vinyl acetate. When treated with chemical processes, the glass becomes much stronger. This design has been in regular use on combat vehicles since World War II. It is typically thick and is usually extremely heavy.<ref>Shah, Q. H.</ref>

{| class="wikitable"
! colspan="22"|Sample thickness and weight for bullet-resistant glass materials<ref>Company specifications from Total Security Solutions and/or Pacific Bulletproof. Retrieved May 9, 2011</ref><ref>{{cite web|author=Nationwide Structures Inc |url=http://www.nationwidestructures.com/ballistic-key.html |title=Ballistic Charts |publisher=Nationwidestructures.com |access-date=2014-08-04}}</ref><ref>{{cite web|url=https://www.youtube.com/watch?v=RnUszxx2pYc |title=Surmet's ALON® Transparent Armor 50 Caliber Test |publisher=YouTube |date=2011-03-14 |access-date=2014-08-04}}</ref>
|-
!|  || Threat Stopped || colspan="4"|Glass Laminate||colspan="4"|Polycarbonate||colspan="4"|Acrylic||colspan="4"|Glass-Clad Polycarbonate||colspan="4"|[[Aluminum oxynitride]]
|-
! Protection Level || (example) || colspan="2"| Thickness || colspan="2" | Weight || colspan="2" | Thickness || colspan="2" | Weight || colspan="2" | Thickness || colspan="2" | Weight || colspan="2" |Thickness || colspan="2" | Weight || colspan="2" |Thickness || colspan="2" | Weight
|-
!  ||  ||  in. || mm || lb/sq. ft. || kg/m<sup>2</sup> || in. || mm || lb/sq. ft. || kg/m<sup>2</sup> ||  in. || mm || lb/sq. ft. || kg/m<sup>2</sup> || in. || mm || lb/sq. ft. || kg/m<sup>2</sup> || in. || mm || lb/sq. ft. || kg/m<sup>2</sup>
|-
| [[UL (safety organization)|UL]] 752 Level 1 || [[9mm|9&nbsp;mm]] 3 shots ||  1.185 || 30.09 || 15.25 || 74.46 || 0.75 || 19.05 || 4.6 || 22.46 || 1.25 || 31.75 || 7.7 || 37.6 || 0.818 || 20.78 || 8.99 || 43.9 || || || ||
|-
| UL 752 Level 2 || [[.357 Magnum]] 3 shots || 1.4 || 35.56 || 17.94 || 87.6 || 1.03 || 26.16 || 6.4 || 31.25 || 1.375 || 34.92 || 8.5 || 41.50 || 1.075 || 27.3 || 11.68 || 57.02 || || || ||
|-
| UL 752 Level 3 (approximately NIJ IIIA<ref>[http://www.armorcore.com/products/level-3/ UL 752 Level 3 Bullet Resistant Fiberglass] click on the lower chart</ref>) || [[.44 Magnum]] 3 shots (5 shots for NIJ IIIa) || 1.59 || 40.38 || 20.94 || 102.24 || 1.25 || 31.75 || 7.7 || 37.6 || || || || || 1.288 || 32.71 || 14.23 || 69.47 || || || ||
|-
| UL 752 Level 4 || [[.30-06]] 1 shot || ||  || || || || || || || || || || || 1.338 || 35.25 || 14.43 || 69.47 || || || ||
|-
| UL 752 Level 5 || [[7.62mm|7.62&nbsp;mm]] 1 shot || || || || || || || || || || || || || || ||  || || || || ||
|-
| UL 752 Level 6 || [[.357 Magnum]] underloaded 5 shots || || || || || || || || || || || || || || || || || || || ||
|-
| UL 752 Level 7 || [[5.56x45]] 5 shots || || || || || || || || || || || || || || || || || || || ||
|-
| UL 752 Level 8 (approximately NIJ III) || [[7.62&nbsp;mm&nbsp;NATO]] 5 shots || || || || || || || || || || || || || 2.374 || 60.3 || 26.01 || 126.99 || || || 18.25 ||
|-
| UL 752 Level 9 || [[.30-06]] M2 AP 1 shot|| || || || || || || || || || || || || || || || || || || ||
|-
| UL 752 Level 10 || [[.50 BMG]] 1 shot || || || || || || || || || || || || || || || || || 1.6 || 40.6 || 30.76 || 150.1
|}
9mm 124gr @ 1175-1293fps (1400-1530fps for Level 6), 357M 158gr @ 1250-1375fps, 44M 240gr @ 1350-1485fps, 30-06 180gr @ 2540-2794fps, 5.56NATO 55gr @ 3080-3388fps, 7.62NATO 150gr @ 2750-3025fps. For all ratings in the above chart; all copper-jacketed lead FMJ, except 44 mg is lead semi-wadcutter gas-check, and 30-06 is LEAD core soft point.