The term ‘pour-over’ is used to describe a host of different brew methods. The common factor is that they brew by percolation, which means that the water passes through a bed of coffee, extracting flavour along the way. Usually there is some sort of material to filter the grounds from the resulting drink, and it can be anything from paper to cloth to a fine metal mesh.
Simple cup-top filter brewers have probably been used since coffee brewing began but the innovations on the theme came relatively late. Only cloth filters were used originally; the invention of the paper filter is credited to a German entrepreneur, Melitta Bentz, in 1908. Now controlled by her grandchildren, the Melitta Group still sells filter papers, coffee and coffee machines today.
The invention of paper filters encouraged the move away from the electric percolator, a terrible brewer which recirculated hot water through the grounds, brewing an incredibly bitter cup. The final death knell for the percolator was the next major innovation in drip-coffee brewing, the electric coffee machine. The invention can be credited to another German company called Wigomat. Variations on the electric filter coffee machine are still incredibly popular today, though not all produce good coffee.
Currently there is a huge range of different brewers, brands and devices on offer, all designed to do this same job and each with its own advantages and idiosyncrasies. The good news is that the principle behind this method of brewing is universal and the technique is easily adapted to different brewers.
THE KEY PRINCIPLES
When coffee is brewed in this way, three variables affect the resulting cup of coffee. Unfortunately they are not independent of each other, which is why precise measurement of both coffee and water is so useful, especially if you are bleary eyed when making the coffee first thing in the morning.
1 The grind of the coffee The finer the coffee, the more is extracted from it as the water passes through. This is because there is a greater surface area, and because water flows through finer coffee more slowly so there will be more contact time.
2 The contact time This is not only how quickly the water flows through the coffee, but also how long it takes us to add the water. We can extend the brew time by adding the water very slowly to increase the extraction of the coffee.
3 The amount of coffee The more coffee there is, the longer the water will take to flow through and the longer the contact time.
To replicate a good brew, these three variables must be kept as consistent as possible. If, for example, someone reduces the amount of coffee by accident, they might assume that the reason the coffee did not brew long enough was due to the grind being wrong. If we do not pay attention, it is very easy to get confused and start to make bad coffee.
POURING KETTLES
When using the pour-over method to brew coffee, the rate at which you add the water plays a role in the brewing process. Pouring slowly and carefully from a standard kettle is difficult to do, and recently there has been a dramatic rise in coffee bars using special pouring kettles. These are usually placed on the stove, but electric models are available. The common factor is that the spout is very narrow, so they issue a very slow, steady stream of water on to the coffee.
Despite their popularity in the industry, I am not convinced they are a truly worthwhile expense for the home-brewer. They do make pouring easier, but if not used properly the water can drop in temperature and prevent the coffee from brewing as well as it could. They could be viewed as an overly serious and complicated gadget when, in truth, we just want to pour water slowly over the coffee. However, if we pour at different rates on different days (something that is very easy to do) then we will get different-tasting coffee from one day to the next, which is not a good scenario.
THE BLOOM
This is the common practice of adding just a little water to the coffee at the start of the brew, usually just enough to get all the coffee wet. When you add the hot water, the grounds start to release the trapped carbon dioxide and the bed of coffee will swell like dough rising. It is typical to wait 30 seconds before starting to add the rest of the brew water.
Despite the widespread nature of this practice, there isn’t a lot of science to justify it. It might be that releasing some of the carbon dioxide helps make the coffee easier to extract, and some studies seem to support this. I think it also adds a pleasant moment in the morning coffee ritual as watching the grounds bloom is a little mesmerizing.
When making pour-over coffee, it is common practice to add just a little water at first to allow the coffee to swell, or bloom.
The strength of a pour-over coffee will depend on the grind size, and the timing and speed of the water flowing through it.
POUR-OVER OR FILTER BREWERS
Ratio: 60g/l. I recommend this as a starting point for all pour-over and filter coffee methods, but be sure to experiment to find your preference.
Grind: Medium/caster (superfine) sugar would be suitable for brewing around 30g coffee to 500g water. You will need to grind the beans more finely if you are brewing a single cup, and more coarsely if you want to brew more (see Grind Size).
1 Grind the coffee just before you start brewing. Be sure to weigh the coffee first. 2 Boil a kettle of fresh water with a low mineral content, suitable for brewing coffee. 3 While the kettle is boiling, place the paper filter in the brewer and rinse briefly under the hot tap. This helps to reduce any taste the paper might impart to the coffee, and also warms up the brewing device. 4 Add the coffee to the brewer, place the brewer on top of the cup or jug and place on the scales. A
5 Wait ten seconds once the kettle has boiled if you are pouring straight from it. If you are using a pouring kettle, decant the water into it immediately. 6 Using the scales as a guide, pour a little water on to the coffee, about twice as much as the coffee by weight. Don’t worry about being too accurate, just make sure you add enough to wet the coffee. I like to pick the cone up and give it a little swirl to make sure all the coffee is wet. Careful stirring with a spoon is another option. Wait thirty seconds before starting to pour the rest of the water. B
7 Slowly pour the remainder of the water on to the coffee, weighing as you go to get an accurate amount and taking into account the water already added. Try to pour directly on the coffee and not the walls of the brewer as water may pass through without really extracting the coffee. C
8 Once you have added all the necessary water, and the surface of the liquid is 2–3cm (about 1in) below the top of the cone, give it a gentle swirl again. This stops any coffee from sticking to the walls of the brewer. D
9 Let it drip through until the bed of coffee looks dry. It should be relatively flat at the base of the brewer. E
10 Discard the coffee and paper, remove the brewer from the cup and enjoy the coffee.
If you are not happy with the resulting cup of coffee, think about what you want to change. I would recommend using the grind to change the flavour of the coffee. If the coffee is bitter it may be overextracted so you should try your next brew using a slightly coarser grind. If it is weak, sour or astringent, try grinding the coffee more finely for the next brew. Very quickly you will know the best grind settings for the coffees you enjoy.
DIFFERENT KINDS OF FILTERS
There are three main types of filters used in pour-over and filter coffee brewing. Each affects the resulting brew by straining out different things.
METAL FILTERS
Like the French press, metal filters only remove the larger pieces of ground coffee. The resulting brew will have some silty sediment in it, and will look a little cloudy. It will have the added body from both the suspended grounds and the oils from the coffee and many people enjoy a cup like this. Metal filters can be used for years as long as the filters are kept clean and washed regularly, as failure to do so will allow oils to build up and become rancid.
CLOTH
Cloth has been used to filter coffee for a very long time. Like paper, it strains out the suspended pieces of coffee but it does allow some of the oil to come through. The resulting cup is very clean, with a richer, fuller mouthfeel.
After use, immediately rinse a cloth filter as well as possible, then dry it quickly. If you leave the cloth to dry slowly it will develop unpleasant flavours, similar to the smell of laundry that has been left in the machine too long. If you use the cloth regularly, keep it stored wet in a glass of water in the refrigerator. If you plan to store a cloth for a long time, put it wet into a ziplock bag and freeze it. Repeatedly freezing and thawing it will cause the cloth to degrade a little quicker, however.
The cloth shouldn’t be allowed to get too stained. For cleaning I would recommend a product called Cafiza, made by Urnex. While this is marketed as an espresso machine cleaner, the original formula was developed to clean the cloths used in very large filter brewers. Dissolve a small amount in hot water and soak the cloth in it, then rinse thoroughly and store.
PAPER
Paper filters are the most common type of filter and they produce the cleanest cup of coffee. They strain out all of the suspended material, as well as any oils that may have ended up in the brew. The resulting cup is a fairly clear liquid, often with a reddish hue. I always recommend bleached white papers, as the unbleached brown papers tend to impart an unpleasant papery taste to the coffee.
