Theory 145/Glass tempering/Rate lens
Tempering Follows Cooling Rate
The claim
Residual stress in tempered glass is set by the cooling rate through the transition range, so faster quenching produces stronger glass.
01Mechanism
The surface solidifies before the interior; differential contraction locks in compressive stress at the surface.
02Prediction
Strength should track cooling rate.
03Refutation
Strength tracking glass thickness would remove the rate.