Tempered glass is widely known for its superior strength, safety performance, and thermal stability. However, once glass has undergone tempering, its internal stresses become highly balanced and sensitive. This makes secondary processing—such as cutting, drilling, grinding, or reshaping—highly challenging and often considered impractical. This article explores the feasibility of secondary processing on tempered glass and the conditions under which it may or may not be possible.

After tempering, the glass surface is placed under strong compressive stress, while the interior is under tensile stress. This stress distribution gives tempered glass its impact resistance but also makes it extremely prone to explosive shattering if damaged. Any localized stress disturbance, such as from cutting tools or drills, can instantly break the glass into small particles. Therefore, in standard industrial practice, secondary machining on fully tempered glass is not feasible using conventional tools.

However, certain controlled methods provide limited possibilities. One approach is to use laser cutting or laser scoring, which applies heat gradually and minimizes mechanical disturbance. Even then, the risk of breakage remains high, and the process is costly and limited to simple modifications. Another method involves chemical de-tempering, where the glass is heated beyond its tempering point to release internal stress before machining. But this essentially reverses the tempering process, turning the material back into annealed glass and eliminating its safety benefits.

For practical and economic reasons, the recommended process remains: complete all shaping, drilling, and edge finishing before tempering. Only after all dimensions and holes are finalized should the glass be tempered to achieve the intended strength and safety.

In conclusion, while secondary processing of tempered glass is theoretically possible under controlled conditions, it is generally impractical, risky, and cost-inefficient. The industry standard is to avoid post-tempering modifications altogether.