Operations on beer: Additions
Regulation 23 of the Beer Regulations 1993 provides the legal basis for addition of substances to beer. A relevant operation in this regulation includes priming. Priming involves adding sugar solution to beer to encourage secondary fermentation, generally leading to an increase in strength. Finings are normally added to cask beers at the packaging stage for clarification purposes but do not increase the strength.
Full details on additions to beer can be found in section 19 of Notice 226.