There seems to have been quite a bit of variation in exactly how long elapsed between pitching and dropping. At some breweries, such as Fullers and Adnams, the wort remained no more than 12 hours in the upper round. At others, it could stay there for two or three days.
Fullers brewing logs recorded the fermentation process in some detail:
|5th November 1941 Fullers X Ale fermentation|
|day and time||temperature||OG||action|
|Wednesday 18:00||63º F||1028.6||pitched|
|Friday 6:30||lowered sluices|
|14:30||collected and pumped|
|Saturday 8:00||67.5º F||1007.8|
|Sunday 9:00||liquor on|
|Tuesday 4:30||59º F||racked|
|Fullers brewing record held at the brewery.|
The fermenting wort was only briefly in the upper round – a mere 9 hours – before being dropped. “Collected” refers to yeast being skimmed off the top for repitching. While “liquor on” is the attemperator being activated.
All in all, the fermentation took around 12 hours short of a full week. Which seems quite a long time for a beer of such a modest gravity.