Agree, good question. I'm not sure if it's detergent or water that might interfere with the crosslinking. I'd just do the best you can to give it as much time before it gets wet. It's not a 24 hour switch where one second after 23:59:59 it all of the sudden is 'cured.' Some parts will cure faster than others. Also if it does bother you, just slap on another coat well after 24 hours. The 2nd coat was a near universal instruction with crosslinking sealants became more popular.