Home Espresso Machine - Variable 2: Grind

Grind is the main factor that determines over- or under-extraction. When you understand your grind size and how to tweak it you will create GREAT coffee every time.

This is because grind size determines the total contact time of water and coffee. If you haven’t yet, read the blog post about Variable 1: Time. We want to be able to use a combination of taste and time to distinguish over-extraction and under- extraction.

First, let’s gain an understanding of what grind we are after.

The table below indicates where espresso coffee sits on the spectrum of grind sizes and it may be useful to note if you use other brew methods.

Now let’s get our hands dirty. If you rub the coffee between your fingers, it should be a similar texture to fine sand. We use this grind size to increase the level of pressure.

Once you make your first adjustment, purge a little bit of coffee, to prevent any leftover grounds from interfering with your newly adjusted shot.

Next, let’s get those tastebuds involved, and don’t forget to pull out your coffee recipe book to start recording some observations.

The first step is to put your coffee into one of three categories: Is it over-extracted, under-extracted, or perfectly extracted? 

If your coffee is tasting sour and the timing is running short, try a slightly finer grind. If it’s on the bitter side and running very long, try going coarser.

It's important to note that when trying different coffee beans (lighter roast, darker roast, single-origin), you will want to adjust the grind size, to make it perfect for that specific coffee.

In the next blog, we cover how to determine the right dose, this will vary depending on your basket size, and type of bean. 

If you’re after more fresh beans, try out our Woodford Blend, our most popular bean for home espressos.

If you are after support for a commercial grinder, contact our café specialist sean@montvillecoffee.com.au