Ventile, long staple cotton, works by absorbing and swelling with water; "closing" the weave and preventing further water from getting in. However, the inner su

Ventile, long staple cotton, works by absorbing and swelling with water; "closing" the weave and preventing further water from getting in. However, the inner surface of the fabric is still wet, so your clothes underneath the jacket can still get wet through capillary action. So to mitigate this, oftentimes manufacturers will use two layers of Ventile or put a wool liner underneath the shoulders. Also, once thoroughly soaked through, it will take just as long to dry as regular ol' cotton. This is why Stotz still treats their version, EtaProof, with DWR. I think Ventile is great, but I think it's better suited for situations where you'll return to a heated shelter at the end of the night.