Center tension

The internal tensile-stress region that balances the compressive stress near the surfaces of heat-treated glass.

Meaning and boundaries

Center tension is an internal stress state, not the geometric center of a pane and not a visible defect.

Why it matters in glass restoration

Inclusions or damage interacting with the tensile zone can contribute to sudden failure of fully tempered glass.

Related terms

• Surface compression
• Residual stress
• Nickel sulfide inclusion

References

• National Glass Association — Engineering Standards Manual, Tempering Division
  Publisher’s original source
• Vitro Architectural Glass — TD-138: Nickel Sulfide and Spontaneous Breakage
  Publisher’s original source
• National Glass Association — Heat Soaking Testing of Tempered Glass
  Publisher’s original source