A quick chat about dosing to your basket size.
When you mention to people about weighing your dose, the response I often get is how much coffee should I use for espresso. The answer, how long’s a piece of string? 🤔
Ok now for the real answer, it all depends on your basket size. In other words there is no set amount to dose, it will come down to the equipment you have (and possibly if you have multiple baskets, how much coffee you want to make).
The How’s
How do we determine this? Well there are many ways depending on your situation. If your machine is stock standard as you purchased it, chances are on the box, in the manual or on the specs from where you purchased the machine, will tell you your basket size in grams. If not, don’t panic, remove the basket from the portafilter and have a look on the side of the basket, a lot will have it either laser etched or printed on the outside.
Wait, you don’t fall into this category either? No stress, there is always good old trial and error if all else fails. So firstly grind out some coffee and weigh it, approximately what you think you normally use as a starting point, let’s say 20g for this example. Add it to your basket distribute and tamp. What we are looking for is adequate head space (aka the gap between your coffee bed and the shower screen). You do not want your coffee bed to touch the screen. A quick test is to lock the handle into the group, then remove it again, if this has disturbed the coffee bed at all you have dosed too much. Time to start over with a little less coffee (how much to dose down I will leave up to your instincts). A simple rule of thumb is to have 2-3mm of head space between the bed and the screen, you can test this by finding a small spacer, or just use the info as a guide. This space is needed for pre infusion, and to leave room for the expansion of the coffee bed when it blooms.
Now that you have determined the right dose for your situation, I would love to see you all weighing your coffee dose in and your yield out (more on coffee ratios to come in the future). For now let’s just keep to the old 1:2 ratio, simple and consistent. If using 20g to dose let’s aim for a yield of 40g, we can measure this by weighing the coffee in the cup. As for making this extraction taste balanced, I would recommend having a quick read on my previous post “a super simple dial in”. This is how we make consistent coffee, grinders (even with timed doses, domestic or commercial quality) generally are not accurate enough to determine dose within an acceptable margin. I have always worked off the tolerance of +\- 0.2g of your target dose, ie. if I aim to dose 20g of coffee, an acceptable dose will be anywhere between 19.8g-20.2g. This is why you will see baristas in specialty coffee shops weighing their doses before extracting coffee.
I have promised to start explaining the why’s in some of my posts to make us all more informed about what is happening within your extractions, giving you the knowledge and power to make your own judgment calls and troubleshoot problems that may arise. In other words make better more consistent coffee!
A coffee puck after a good extraction, using correct dose for the basket.
The Why’s
Leaving headspace in your basket leads to a higher, more even and consistent extraction. This happens for a couple of reasons:
The shower screen will disperse water onto the coffee bed with 0 bar of pressure until it fills up and begins to pressurise. Allowing the bed of coffee to slowly saturate. This acts like a mini pre-infusion, reducing the chance of channeling and increasing extraction.
A shower screen allows water to travel through set holes in the screen, if the coffee is too close to the screen, the water will travel directly from the holes in the screen onto the coffee bed, not allowing it to evenly saturate as designed, leaving dry spots in the coffee bed leading to an uneven extraction. this can also lead to channeling in the areas being hit with too much water.
One final note, studies have shown having slightly more clearance than 2-3mm will create a wet soggy puck (slightly messy), however it doesn’t have any significant effect on the espresso and still will react nearly the same as having the recommended head space. With that being said, staying within the optimum dose is best practice.
Hope this helps you brew better coffee, and that maybe you learnt something new. Feedback is always welcomed, as is a a friendly coffee chat. Drop me a message here or on Instagram.
Take care & make great coffee,
Lars ☕️😎
That’s totally correct Simon! Just disinfect that coin before putting it on your coffee bed lol.
I've heard that a quick way to check for that golden 2-3mm mark before the screen is to put a $1 coin on top of the ground coffee and insert into the machine. If it makes a slight indent into the coffee where the coin was, that's the right level to aim for.