A coffee percolator has two chambers, one beneath the other, linked by a vertical tube. Water in the bottom chamber is heated -- some percolators have their own heating element while others must be heated on the hob -- and travels up the tube. The water then filters down through the coffee grounds and returns to the bottom chamber. This process is repeated continuously, transforming the water into coffee. Any brand of coffee can be used, but it must be coarse ground. Too fine of a grind will lead to sediment in the bottom of your cup.
Choose any brand of coffee you like. Whichever brand you purchase, the beans will either be totally Arabica or an Arabica/Robusta blend as these are the only two coffee species used in commercial coffee production. Arabica has a mild, aromatic flavour with a low caffeine content. Robusta is sharp and bitter with a caffeine content twice as high as Arabica. The website How to Brew Coffee recommends using beans that are very smooth, low in acidity and ground even more coarsely than those destined for a French press coffee maker.
Grind whole coffee beans at the most coarse setting on your grinder as you need them. Store beans in an air tight container -- preferably one that provides vacuum storage -- and keep them in a cool dark place.
If you buy pre-ground beans off the supermarket shelf or beans ground at the store when you buy them, look for one way vacuum bags. These bags incorporate a valve that allows gas to escape but prevents oxygen from getting in, thereby keeping the coffee fresh longer.
Pour cold water into the bottom chamber of the percolator, allowing 170 to 227gr. per cup. Insert the tube and the top chamber, making sure the water remains below and does not touch the upper chamber. Place 2 tsp coarse ground coffee in the top chamber for each cup of coffee. Turn on the percolator if it has its own heating element, or place it on the stove.
Do not allow coffee to boil ... boiling leads to over-extraction and a bitter taste. An electric coffee percolator will automatically stop brewing as the coffee reaches the boiling point. This indicates the coffee is ready to drink. Keep watch on a hob percolator and remove it from the heat once the brewing process is well under way but before the coffee boils.
Pour coffee in cups that have been previously warmed with hot water. Serve according to taste -- black, with or without sugar, or with cream, half-and-half or milk.