You can fine your beer with gelatin in the fermenter (primary or secondary), or in the keg/bottles.
Beer should be cold (32-40F), so the fining process is more effective, and the longer the wait the clearer the beer, although you should see results after 48 hours of having added the gelatin.
Ingredients for 5 gallons:
- One teaspoon of clear plain (no flavored) gelatin.
- 200 ml of sterile water.
- Mix gelatin and water and let it sit for a couple of minutes to let gelatin particles to dissolve with the water.
- Heat the mixture to 150-155F (65-70C) to pasteurize the solution.
- Stir again and verify that chunks have disappeared.
- Add this mixture to your beer. Some brewers prefer to add it to the secondary fermenter a few days before bottling or kegging, and others prefer to add that to the keg in the kegging process.
- If pouring on the keg, agitate a bit the keg to ensure the gelatin mixes properly with the beer.
- Return your keg/fermenter to the fridge/kegerator for a couple of days.
- If using a keg, ensure to remove any oxigen that got mixed in during the process.