Compac CG copper finings are the semi-refined, tablet form of the seaweed species Euchema cottonii. This species is rich in the kappa isomer of carrageenan. When added to boiling wort, kappa carrageenan reacts strongly with soluble proteins, notably the proline rich haze precursor fraction.

When the wort is cooled the carrageenan protein complex becomes unstable and precipitates out of solution. The clear wort that results produces a beer with enhanced processing characteristics, notably improved hot break compaction in the whirlpool; improved yeast vitality during fermentation; improved filtration – longer filter runs and improved beer haze and colloidal stability.