John Colvin, a contributor to the EU Standards Committee developing the standard for heat soaked toughened glass, maintains that correct heat soaking can help prevent breakage. Heating the toughened glass (as long as the temperature stays below 290 degC) makes NiS breakages occur much more quickly and safely during the production process. This temperature effect is why spandrel panels, which can get very hot because of the insulation behind them, appear to be more susceptible. They are not, but any fractures happen much sooner than with clear glass. While most "spontaneous" breakages do not result from NiS, they are known to be a cause. But beware the attribution of toughened glass breakage to NiS where this has not been positively identified - there may be more serious reasons. More of this paper can be viewed on: www.glassage.com
