One of the problems with brewing your own cider is cloudiness, or chill haze, being introduced into the final product. Fortunately, this problem can be solved by the addition of simple, unflavored gelatin. The process of using gelatin to clear cider is called fining, and gelatin is a fining agent. Gelatin is an inexpensive and highly effective method. It works by attaching to the haze-causing particles within the liquid and settling them to the bottom, where the clear liquid can be racked off. Fining your brew should occur once it has finished its secondary fermentation.
Boil a cup of water in a small saucepan. Once you have it boiling, remove it from the heat and place it in a measuring cup.
Measure out about 1 tsp of unflavored gelatin. Once the water has cooled to near room temperature, add the powdered gelatin and stir. Let this sit for about 20 minutes.
Stir the solution into your brew slowly so as not to introduce oxygen. Take your time and make sure it is mixed in thoroughly. Alternatively, you can add the solution to another bucket or carboy, and rack off the secondary fermentation onto the solution. Once again, make sure the gelatin solution is thoroughly mixed in.
Let the solution sit for three to five days. It should be very clear with visible sediment on the bottom at this time. You can now rack the cider off of the sediment for bottling or kegging.
You can use this method for unfiltered, non-alcoholic cider as well by adding the solution to the jug and shaking. Gelatin is an animal product. If your goal is to create a vegan cider, use a non-animal fining agent like isinglass. This same method applies to both beer and wine as well.
Do not add gelatin to your primary fermentation. It will precipitate yeast out of the fermentation and affect the taste of your finished product.