Brewing coffee is a highly preventative activity. We would argue that brewing coffee is more closely related to prevention than to creation. The two main issues we look to prevent in brewing are called Channeling and Bypass.
Channeling occurs when water flows continuously through similar paths, divots, or channels inside of a bed/puck of coffee. Channeling often occurs when grounds are too fine and therefore lack proper permeability for water to flow in an even fashion. Simple ways to minimize channeling are:
- Spinning- When brewing in a percolation filter method, every time you pour you create an opportunity for channeling to occur. If you therefore move your brewer in a circular motion while pressing down slightly and focusing on the bottom of the coffee bed, you can break up some channels and likely create a more even flow of water. It should be noted that too much spinning (or really any at all) CAN increase the likelihood of bypass- by spinning you’re propelling water out to the sides and slightly out through the filter.
- Proper preparation: Channeling occurs when things are not in place for water to flow properly. If you can prepare your bed evenly (just give it a good light shake), pour evenly, and grind coarse enough for water to flow properly (while still grinding fine enough to allow the water to extract what it can), you’ll likely minimize channeling tremendously.
Note that these are ways to minimize channeling- channeling will likely occur in every brew in some fashion.
Bypass occurs when water flows out and around a bed of coffee rather than through the bed itself. This issue often occurs hand in hand with channeling (particularly in filter coffee) if the coffee is too fine of a grind, or if your slurry height (the coffee and water incorporated inside of your brewer) is too tall. This is why something like pouring a long single pour with a melodrip is ineffective. Brewing coffee with a single pour would actually be more effective with a bare kettle given that you are at more of the subject bed of coffee with your stream of water before it bypasses (The Melodrip is one of the best designed brewing tools on many levels in our book, but to use one it is much more effective to pour in smaller stage pours.) Simple ways to minimize/prevent bypass are:
- Stage Pouring: Rather than pouring all of your brewing water into your brewer in use, cut your brew water into different parts and different stages. Doing this will keep your slurry level lower and minimize bypass.
- Low water levels: Riding on the tail of the first method to minimize bypass, if you consciously keep a low water level while brewing, you will likely minimize bypass. One way to effectively do this is using a Melodrip to evenly distribute small amounts of water; a melodrip is much more efficient in effectively distributing water when pouring in pulses of 15-30 grams.
- Thick filters: The thicker the filters, the slower the BDR (beverage drip rate), and this is partially due to a lesser amount of bypass. Thicker filters, logically, will allow less water to flow as evenly, hence minimizing the amount of water that will flow out of the sides of your brewer.
- Prevention: Methods exist to completely eliminate bypass. Methods like the Tricolate and Aeropress+MD technique are great ways of doing this (though much more time consuming in the way of preparation), but also Espresso, for the most part, has no bypass occurring (though, if at high pressure can have lots of channeling).
When brewing in the future, look to minimize these two issues. If done effectively, you will likely end up with a tasty cup-o-joe :)