Hvorfor fungerer E-glas ikke ved 900 °C?

<span style='box-sizing: border-box; margin: 0px; padding: 0px; color-scheme: light; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; color: rgb(0, 0, 0); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; font-size: 14px; text-align: left; background-color: rgb(255, 255, 255); float: none; display: inline !important;'>Hvorfor fungerer E-glas ikke ved 900 °C? <br style='box-sizing: border-box; margin: 0px; padding: 0px; color-scheme: light; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; color: rgb(0, 0, 0); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; font-size: 14px; text-align: left; background-color: rgb(255, 255, 255);'><span style='box-sizing: border-box; margin: 0px; padding: 0px; color-scheme: light; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; white-space: normal; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; color: rgb(0, 0, 0); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; font-size: 14px; text-align: left; background-color: rgb(255, 255, 255); float: none; display: inline !important;'>Glasfibrene kan kun tåle op til 550 °C. Derefter smelter de enkelte fibre sammen, og fletværket bliver til et stykke glas. Det er dog flot at se fletværksstrukturen, som stadig kan skimtes i glasset.