The DIY stopper must use a low-durometer (soft) elastomer with high thickness-to-diameter ratio to maximize the Poisson-driven radial seal.
| Stopper type | Initial leakage (mL/min) | After 500 cycles | Failure mode | |--------------|--------------------------|------------------|---------------| | Commercial rubber disc | 2.1 | 12.5 | Cracking at stem junction | | Commercial pop-up | 0.5 | 8.3 | Corroded pivot, misalignment | | DIY silicone + weight | 0.0 | 0.2 | None; slight surface wear |