Getting a coffee grinder is great way to improve your coffee experience. To make coffee, roasted coffee beans need to be turned into smaller pieces so it can be brewed.
Why Coffee Needs to be Ground?
Coffee beans are ground so the water can flow through, touching more of the coffee surface. The more coffee the water touches, the more coffee flavor is extracted. Finer grinds increase contact area and increase the flavor extraction rate.
The size of the coffee grind will also change how fast the water flows through the coffee. The coarser the grind, the faster the water flows. The less time the water is in contact with the coffee, the less it extracts the coffee flavor.
A higher extraction rate means you need less contact time with the water.
The art of coffee making is to balance the extraction rate, flow of water and contact time with the water and the grinds.
How Small Should Coffee Grinds be?
Different coffee making methods work best with different grind sizes. Making a coffee with longer contact time with the water will generally require a coarser grind. Other factors like water temperature, types of filters and the pressure the water is forced through the coffee grinds with also come into play.
Coffee Method and Grind Size Chart
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Cold Brew Coffee
Extra Coarse Grind, although is not so important due to the low temperatures making the extraction rate very slow.
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French Press
Coarse Grind.
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Chemex
Medium - Coarse Grind.
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Drip
Medium to Medium Coarse Grind.
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Cone Shaped Pour Over Brewers
Medium Grind to Medium Fine Grind.
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Siphon Brewers
Medium Fine Grind.
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AeroPress
Medium to Fine Grind depending on brewing technique.
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Espresso
Fine to Very Fine Grind. The grinds are compacted and the water is forced through quickly at pressure, which means a short contact time with the water is needed.
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Moka Pot / Stovetop
Medium to Fine Grind.
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Turkish Coffee
Super Fine Grind.
Bitter Coffee
Bitter coffee is often caused by having grinds be in contact with the water for too long, or the grind size being too fine for your coffee making method. This can lead to over-extracted and bitter coffee.
Weak Coffee
A coarser grind can mean the water flows through too quickly and does not extract enough coffee, leaving you with a weak coffee flavor.
Fresh Coffee
You can buy pre-ground coffee, but coffee gets stale. Once ground, the coffee becomes stale much more quickly (even when vaccuum sealed), so it works best if you grind just before you brew your coffee.
Aim for Consistency
You want the coffee grinds to be the same size as each other. You also want the same results each time, so when you get the coffee how you like it, you can make it the same way again.
Types of Grinders
There are blade and burr grinders.
Blade vs Burr Grinders
Using a spinning blade to chop up the coffee beans leads to inconsistent sizes. As you grind, the coffee bounces around when struck by the blades, some turning to super fine coffee particles and others being a larger size. These inconsistent sizes can also cause clogging problems when brewing.
Another reason for inconsistent sizes is the blade grinder will keep the ground coffee and the uncut beans in the same compartment, while a burr grinder normally feeds the ground coffee into a different compartment.
The burr grinder feeds the coffee beans into the burrs in a controlled manner, leading to very consistent results. There are flat and conical grinders, but the idea is the same. The beans are fed through the burred surfaces, one surface moving and the other stationary. The required size can be changed by adjusting the distance between the surfaces. Further apart for coarser grinds, or closer together for fine grinds.
Blade coffee grinders are very cheap, but you can get well priced burr grinders these days, so it is recommended to use a well regarded burr grinder.
Some people like blade grinders so they can be used to serve extra duties like breaking down spices, herbs, nuts etc. If you have never tried a burr grinder, see if you can get your hands on one and see if it makes a difference to your coffee.
Heat and Coffee Grinding
Heating your coffee while grinding is unwanted because it may change the taste of your coffee. Between flat and conical burr grinders, conical seem to be favored for reducing heat when grinding.
If you are going to use a blade grinder, some people recommend pulsing to reduce heat.
Grinding Speed
It is recommended to get a grinder that works at low speed. High speed grinding can heat up the beans and may also increase the static charge.
Static Charge and Coffee Grinding
Static charges are undesirable when grinding coffee. The static charge causes the coffee to stick to the container it is in, or it can make the coffee fly places you do not want. This makes it hard to empty the grinds and can make cleaning difficult.
There are many causes of static charges, but here are some techniques that can reduce static in your coffee grinds:
- Increase the humidity of the whole beans just prior to grinding by spraying a tiny amount of water mist on them.
- Wait 15 to 30 seconds after griding to allow the static charge to reduce and then tap to help the grinds fall out.
- Get a grinder with Inherently Dissipative Properties (IDP)… meaning a special plastic or other material like glass that tends not to hold a static charge as long.
- Some people mention a different type of coffee bean can reduce static.
- A few people also mention they have had success putting metal foil in the grind container.
Dosing versus Non-Dosing Grinders
Dosing grinders are normally used with espresso makers. The doser is a special catchment area. There is a hole in the bottom of the doser. When you trigger the release (via a lever, or button) the coffee grinds fall into a container (normally a portafilter that is then used in the espresso machine).
Advantages of Coffee Grinders
- Grinding before you brew coffee is the best way to avoid stale coffee.
- You can grind on demand. Whole beans will remain fresh longer than ground coffee.
- It can be hard to know how old pre-ground coffee is.
- You can change the grind size to suite the style of coffee you are making.
Downsides to Coffee Grinders
- You need an extra device, i.e., the coffee grinder.
- This device may break.
- Some people do not like hand grinding and find it too much effort
- Small and manual grinders may take a long time if you are making many coffees.
- Grinding is an extra step, so it takes longer to make your coffee.
- You need to store the grinder, or carry it with you.
- Some coffee grinders are quite large.
- Electric grinders may need a power point.
- Cleaning and maintenance.
What are we looking for in a grinder
- Good Build Quality
- Consistent Grinds
- Cleaning
- How easy and convenient is the grinder to clean?
- Maintenance
- How often do you need to maintain the device to keep it working in optimal condition and do you need professional support?
- Spare Parts
- Can you get spare parts and how costly are they?
- Capacity
- How many coffees are you likely to be making at a time?
- Size
- Do you have space to store the grinder. Small grinders are great when on the move, or have you got the space in your kitchen for a larger grinder.
- Grind Range
- If you like different styles of coffee, you may need a coffee grinder that lets you dial in different grind settings.
- A handle that does not come off easily while grinding.