Rancilio Silvia Grinding Espresso Beans

Grinding Basics

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The Importance of Having a Good Grinder

Having a good quality coffee grinder is one of the most important elements of making good espresso. A good espresso grinder must be able to achieve a very fine grind of coffee. The fine grind size creates a nice large surface area for the water to contact maximizing flavour when brewing. Look for an even ground size from your grinder to ensure a smooth extraction. Aim to achieve a fine, flour like consistency.

An example of two common grind sizes

ground espresso beans

Grinding’s Impact on Extraction Time

A 1.5 ounce espresso shot should take 20 to 30 seconds to extract.

  • If your shots are taking less than 20 seconds you will need to use a finer grind and/or make sure you are tamping with a full 30 pounds of pressure.
  • If your shots are taking longer than 30 seconds to draw they will likely be over extracted and you will need to use a coarser grind.

Never pre-grind and store coffee

Always grind immediately before you brew. Pre-ground coffee has a much greater surface area and gets stale very quickly when exposed to air which will ruin your shot.

Humidity

Coffee is also greatly affected by humidity and temperature. Beans and especially ground coffee absorb humidity when present in the air. This causes the coffee granules to swell and they will tamp down more compactly, offering greater resistance to brewing water. Due to this, you will need to grind the beans slightly more coarsely in moister weather. This will increase the extraction flow rate and maintain your shot timing. Conversely, when it is dry out you will need to use a finer grind to slow down the extraction.
When adjusting your grind make sure you empty any leftover grounds out of the grinder/doser before grinding on the new setting or you will mix the old with new.

Clumping

Lower quality grinders often cause clumping of the coffee grinds. This uneven consistency causes uneven extraction and poor shot quality. If you have a grinder that is prone to clumping try using the Weiss Distribution Technique covered in the Leveling & Distribution lesson.

Types of Grinders

There are two main types of grinders you will encounter, blade grinders and burr grinders.

Blade Grinders:

While very common and inexpensive, blade grinders are not a good option for espresso. Their high speed chopping motion causes a wide range of ground sizes and the friction heats the coffee which is undesirable.
Examples of common blade grinders

Burr Grinders

The second type of grinder is the Burr grinder. These grinders use two sets of evenly spaced abrasive elements called burrs made metal or ceramics. They can be either conical or flat in shape, both of which work well. When operating, one burr remains stationary while the other is powered by the motor. The distance between the burrs dictates the size of your grind. Good quality burr grinders use heavier burrs and spin at lower speeds to reduce the amount of frictional heat the coffee is exposed to. The less heat you expose the beans to during the grinding process the better your flavour. Usually lower cost burr grinders spin their burrs at higher speeds, causing more friction and heat.

Grinding Burrs:

Although burr grinders are your best choice for espresso, the average home burr grinder will not be sufficient. They will not grind the beans nearly fine or evenly enough and may cause clumping of the grounds. You will need to move into a “prosumer” or commercial grinder to really make the most of the Silvia’s capabilities.

Stepped vs Stepless Adjustment

One factor you might encounter when looking for grinders is the choice between stepped and stepless grinders. Stepped grinders provide coarser adjustsments, moving click by click, whereas stepless grinders adjust smoothly and allow infinitely finer control over your grind. Cheaper grinders usually only come in a stepped model, you have to move up to the higher end Mazzer or Macap grinders to get this functionality.

Next: Read about good grinders to pair with Miss Silvia

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