Viracon has been offering a heat soak test option since 1984 and has not had a single incidence of spontaneous breakage occur in heat soak tested glass. With the two-hour dwell time, Viracon is confident the process has minimized the potential for breakage to its lowest level. There are situations where tempered glass simply must be used because of its superior strength and break-safe characteristics. In these situations, Viracon provides this alternative service as a means to avoid the potentially serious occurrences of spontaneous breakage.