The explosion-proof and crack-resistant performance of double wall glass stems from the dual support of a double-layer vacuum structure design and high borosilicate glass material properties. It addresses the pain point of single-layer glass being prone to cracking due to temperature differences in two dimensions: material heat resistance and structural stress dispersion.

1. High Borosilicate Glass Material: Basic Guarantee for Temperature Resistance and Low Expansion

Premium double wall glass generally adopts high borosilicate glass, whose silica content is as high as over 80%. Compared with ordinary soda-lime glass, its thermal expansion coefficient is reduced to one-third. This property ensures that the cup body will not generate internal stress due to excessive differences in thermal expansion and contraction between the inner and outer layers under drastic temperature changes, fundamentally reducing the risk of cracking. Meanwhile, high borosilicate glass features higher toughness and better impact resistance than ordinary glass, and can withstand pressure caused by a slight collision.

2. Double-Layer Hollow Structure: Isolating Temperature Differences and Dispersing Thermal Stress

There is a vacuum interlayer between the inner and outer walls of double wall glass, and this structure is the key to explosion and crack resistance. When boiling water or ice water is poured into the cup, heat or coldness is confined to the inner wall. The vacuum interlayer can effectively insulate temperature conduction, keeping the outer wall close to room temperature at all times.

This design avoids the problem of single-layer glass that "excessive temperature difference between inner and outer walls → uneven local expansion/contraction → stress concentration leading to cracking". It allows thermal stress to be evenly distributed on the respective structures of the inner and outer walls, greatly improving the safety of use.

3. Reinforcement by Detailed Processes: Eliminating Stress Weak Points

The explosion-proof and crack-resistant performance also relies on refined production processes: first, the cup mouth and bottom are rounded and polished to eliminate sharp edges and burrs—these parts are weak points where stress is prone to concentrate, and stress overload cracking can be avoided after polishing; second, some high-end products fill the double-layer interlayer with inert gas to further optimize the heat insulation effect and enhance the structural stability of the cup body; third, the uniformity of wall thickness is strictly controlled, with the thickness deviation between the inner and outer walls not exceeding 0.2mm, ensuring balanced stress when conducting heat and cold.

4. Safety Guarantee for Usage Scenarios

The double-layer structure also reduces the composite cracking risk caused by "thermal expansion and contraction + external impact". The characteristic that the outer wall does not get hot reduces the probability of users slipping and dropping the cup due to high temperature; at the same time, the hollow interlayer can buffer external impact force. Even if the cup is accidentally dropped, the impact force will be dispersed by the double-layer structure, which makes it less likely to cause the cup body to break directly.