I came across this method mentioned on some Aussie Beer Forums. Apparently water restrictions in the last “Big Dry” motivated experimentation. Some brewers use special airtight food grade quality containers but I haven’t found that necessary.
My version is when I finish the wort boil I just wrap the stock pot(in my case 9 litres) with clean beach towels secured with bungy cords and leave until the next day to tip into the fermenter. The towels serve to ensure no insects or bugs get into the pot. Some folks soak them in a sanitizer first but I don’t, so far, no bad results.
The advantage for me is to defer for 15 hours transferring the wort as all to often its getting near dinner time with all the usual distractions. Previously being not willing to muck around with cooling coils I would freeze a couple of dozen water bottles and put into a bath,etc. I am not sorry to leave out that step.
This isn’t my last word as it is still a work in progress. I boil the hops loose on the basis it is more fully dissolved. It has been suggested to me that leaving the wort overnight on the hops could cause the excessive bitterness which has been a feature of some recent brews. I had put it down to overdoing the amount of hops added. Perhaps a bit of both but I will reduce the amount or add later and sieve (or put in a hop bag and remove) before wrapping in towels.
Next time, I’ll tell you my adventures in oxygen: oxygenation and oxydisation … the good, the bad and the ugly!
For more information on this topic a search on Google will turn up all sorts of interesting leads.