Tempering process increases the strength of glass many folds, offering a greater resistance to breakage. However, the raw-material used in the manufacture of tempered glass is not free form raw-material used in the manufacture of tempered glass is not free from certain defects including Nickel Sulfide inclusions, which put empowered glass at potential risk of spontaneous breakage. The amount and size of these inclusions vary from glass to glass. It has been a challenge for the float glass manufacturers to produce a glass free from nickel sulphide (NIS) inclusions.
Nis inclusions change their structure and volume during the heating process of tempering. This changed state is 'trappod' during the quenching process. So at room temperature, the Nis inclusions tend to change back to their original state, which having bigger volume, cause spontaneous breakage. This changing back of state could happen in a few minutes to a few years, making it unpredictable when the tempered glass may break.
At GSC, we realize the implications of spontaneous Temperdglass fracture and the much inconvenience caused. Therefore the concept of heat-soaking is defined as the transfer of potential on-site breakage to breakage in the factory under a controlled process of accelerating the inversion of the nickel sulfide inclusions to their low temperature phase. In all probability, the glasses theat have Nis inclusions, will break during this heat soaking process.
While heat-soaking does not guarantee that breakage will be completely eliminated in installed tempered glass, it reduces the changes drastically. Studies have been conducted worldwide indicating the reliability of heat soak test to as high as 98.5%.
All fully tempered as well as heat strengthened glasses for a project can be heat-soaked in our heat-soak oven. We can heat soak a glass of maximum size 2400 mm in height by 3660 mm in width.
