I really enjoy your videos and that was a really good presentation of why some companies heat soak tempered glass because of the the potential of nickel-sulfide inclusions.. Very informative and well presented, however I would suggest that there are a couple of limitations involving heat soaking that are worth considering prior to going fully into the heat soaking route. First, if the glass was floated in Europe or Asia (especially China), then nickel sulfide inclusions can be an issue, but North American floats don't use nickel anywhere in the process (including furnace materials) so that nickel sulfide inclusions are not an issue with North American glass. The second, and possibly more important, reason is that heat soaking could actually cause tempered glass that survived the process to spontaneously shatter in the field specifically related to the heat soak prior to field installation. In order for the inclusion to cause the glass to shatter it has to be located within the transition boundary of the compression and tension layers. While heat soaking should result in causing inclusions that are within the transition area to expand and likely cause the glass to break, if the inclusion is fully located within either the surface compression layer or center tension layer then they are harmless and should not result in glass breakage in the field nor during the heat soaking process. However, it is possible in some cases that heat soaking could migrate an otherwise "safe" inclusion into the transition boundary during the cycle, without causing the glass to shatter during the process, that could result in a tempered glass that might very well fail in the field after surviving the heat soaking process, And while I am not suggesting that heat soaking should be abandoned, the potential for field breakage of tempered glass because of heat soaking should also be taken into account as well when considering using that process.
Alex, great job on these videos. Just watched everyone of them. Answered so many questions I’ve had.
Hey Robert, thank you! that's an awesome comment to get. Much appreciated.
I really enjoy your videos and that was a really good presentation of why some companies heat soak tempered glass because of the the potential of nickel-sulfide inclusions.. Very informative and well presented, however I would suggest that there are a couple of limitations involving heat soaking that are worth considering prior to going fully into the heat soaking route.
First, if the glass was floated in Europe or Asia (especially China), then nickel sulfide inclusions can be an issue, but North American floats don't use nickel anywhere in the process (including furnace materials) so that nickel sulfide inclusions are not an issue with North American glass.
The second, and possibly more important, reason is that heat soaking could actually cause tempered glass that survived the process to spontaneously shatter in the field specifically related to the heat soak prior to field installation.
In order for the inclusion to cause the glass to shatter it has to be located within the transition boundary of the compression and tension layers. While heat soaking should result in causing inclusions that are within the transition area to expand and likely cause the glass to break, if the inclusion is fully located within either the surface compression layer or center tension layer then they are harmless and should not result in glass breakage in the field nor during the heat soaking process.
However, it is possible in some cases that heat soaking could migrate an otherwise "safe" inclusion into the transition boundary during the cycle, without causing the glass to shatter during the process, that could result in a tempered glass that might very well fail in the field after surviving the heat soaking process, And while I am not suggesting that heat soaking should be abandoned, the potential for field breakage of tempered glass because of heat soaking should also be taken into account as well when considering using that process.
Greg, these are all really good points. We appreciate you taking the time to write all of this.