Every time I make coffee it seems to taste different, and I've found there is a lot more room for error with the manual drip-brew method than using a Moka coffee maker or an automatic drip-brewer.
There are too many variables to list, but I'll try:
- Type/color/brand of filter
- Amount of coffee
- Wetting the filter
- Wetting the grounds
- Amount of time between wetting the grounds and pouring the rest of the water
- Plastic / ceramic / glass cone
- Coarseness of the grounds
- Rate of water flow
- Temperature of water
- Height from which to pour water
- Trickling water or constant pour
- Clockwise / counterclockwise / or straight-on pouring
- Whether to fill it up to the brim and let it seep down or be patient and pour a little at a time
- And many more.
But what are the most important factors (either from this list or anything I might have missed) that I need to do every time to ensure that the cup is a most excellent brew? How do those factors actually affect the brew and why?
Please include only factors specific to, or of particular import to this method of coffee brewing.
Best Answer
Background
The manual drip technique (AKA "filtercone brewing") and an automatic drip-brewer are very similar; both involve pouring water through a conical filter into a vessel. The difference is that an automatic drip-brewer maintains consistent and hopefully ideal conditions, so when you drip-brew manually, you are essentially trying to recreate the environment inside an automatic drip-brewer.
Much of the following is derived from sweetmarias.com - my constant source for coffee information.
Customizing your coffee
The most important variables in terms of how much they affect the end result also happen to be easily isolated variables that you can control simply with tools. They are:
Temperature of the water
The best temperature is when the water is just coming to a boil, around 200° F or 93.3° C. An automatic drip-brewer will generally maintain a temperature of between 195° F and 205° F.
Water that is too cold won't extract enough of the oils and will give you flat, flavorless coffee. Water that is too hot will extract a lot of the proteins and give you very bitter coffee.
This is simple to control for; just use a thermometer, or learn how to recognize when the water is just about to boil.
Coarseness of the coffee
The grind (obviously, a fresh grind especially) is important here, as it is with any distillation method. What you need to remember is that you are matching the temperature and pressure of extraction.
For high pressure extraction (espresso), uniformly fine grind is preferred to ensure that the water does not shoot past the puck too quickly. For lower pressure methods (i.e. manual drip), you want a medium grind to ensure that the water passes easily but not too quickly.
Again, this is simple to control for; just use a good, reliable coffee grinder.
Ratio of water to coffee grounds
This is mainly a matter of personal preference. Figure out what you like, but ensure that this is the final variable you are isolating. Use a measuring spoon, start at 8 grams (about 1 rounded tablespoon) per 5 oz water, and start experimenting from there.
Improving your consistency
Once you've dealt with the obvious factors above, proper technique becomes essential to improving on the consistency of your brewing process. You'll want to watch out for:
Steady heat during the pour
Depending on the material your filter cone is made of, it may take a while to heat up, which means that initially the water will lose heat to the cone and become too cold before it passes through the coffee.
You can compensate for this by pre-heating the cone. Use hot water for this; don't use the microwave, especially if it's a plastic cone.
Ceramic cones are more heat-stable than plastic, but will take longer to heat up, so it's more important to pre-heat them. You probably don't need this stability because the water shouldn't be in the cone for too long - unless you're brewing a full pot. Most pour-overs should really only be for about 20 ounces of coffee.
Pour Time
The best automatic coffee makers have a sprinkle head and pour out over a deliberately extended period of time, as opposed to shoving the coffee through in a rush. This is because you are trying to extract flavor as thoroughly as possible, and quick is not thorough.
Maintain a slow, steady pour. Trickling is less effective since it will cause an uneven leaching from the grinds, so be wary of this. Submerging is even less effective because you will lose heat from your water as it sits there. This is probably the most important part of a good brewing technique.
It should take 4-5 minutes, pouring evenly over all the grinds, to extract a full 10 cup pot. Hopefully your arm is strong or you're only doing 1 cup.
More practically, you will want to refer to this chart on specific infusion times: For example, for a #4 filter, and 20 ounces of coffee, you will want to spend 2 minutes and 30 seconds on the infusion (they recommend 32g or ~4 rounded Tbsp of coffee).
Wetting the filter
This applies when your filter falls down (as wetting it keeps it up) - not a big problem with conical filters. That said, in some cases rinsing off your filter is preferred in the event that your filter gives an off-flavor. I personally have never encountered this with unbleached filters.
Wetting the grounds
There are two schools of thought on this. Some say to do it, others say not to do it because it locks up the oils or stales the coffee when done too far in advance.
In the case of a straight pour over filter, non-vacuum, sweetmarias.com recommends "blooming the coffee 15-30 seconds" by sprinkling with a pre-pour. (I assume that's what 'wetting the grounds' meant. In my experience, premature moisture is less of a problem for beans with more sugar, i.e. lighter roasts.)
As for time between wetting filter/grounds, you should minimize wetness of coffee in the interest of freshness by thermal conservation, or refrain from either step.
Height of pour
This matters mainly because you don't want to splash water or grinds everywhere, but more importantly you don't want the water to lose heat on its way down by pouring too far.
Rotation of pour
Pick one, do it evenly across all grinds. The important thing here is consistency.
Miscellaneous tips and tricks
According to sweetmarias on the quantity of coffee:
Consider removing the drip before the final drops go through. According to Voilley et al., Eval., 287:
So watch out for those last few drops, because they will tend to have lost some heat and will thus leach more solids with fewer aromatics, resulting in more bitterness.
Now go enjoy some hand cranked coffee consistently.