Steps in puck preparation

Puck preparation (puck prep): The preparation stage where you make the coffee puck flat and of consistent density. It's not easy!  You can use tools such as coffee leveler, puck rake, coffee dosing ring, and others to achieve balance extraction.

Puck raking for puck preparation (puck prep).
This is the process which aims to achieve coffee puck balance and even density before tamping the coffee into a flat coffee puck so that the water will flow through the coffee puck evenly and your extraction would be well-balanced.
There are several methods and instruments designed for this purpose and puck rake is one of them. Using this simple and inexpensive tool helps you to break up the clumpy coffee ground (if there is any from your grinder) and to make the coffee ground is evenly dense but also fluffy like cotton candy which is good for even extraction.
There's efficiency in puck raking, unlike some methods which will impact the puck density before tamping.
Let me explain further with illustrations,
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examples above, trying to catch the ground evenly just like the bottom illustration, will give significantly better results.
On the other hand, catching the ground unevenly will result in higher risk in channeling or uneven extraction as the puck consists of uneven density.
You may ask, what if I made a mistake by overlooked and caught the ground unevenly?
It’s fine, there will be a solution explained in the next steps.
So here we go step by step of puck prep:

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Step 1, dosing

It's recommended you confirm the dose of your recipe, I would suggest you add just a little bit more, for example, if your recipe is 18g, you would put in 18.2g of dose, then you will get 18g coffee ground, as about 0.2g would be lost, as explained, it's the retention from your grinder, for some grinders, I will put in extra 1g, but depends on what grinder you're using (i.e, flat burr, conical and size of the burr).

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Step 2, grinding

As mentioned, during grinding you have to catch the coffee ground as evenly as possible to avoid any unevenness.

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Step 3, place at flat surface.

It’s important to place the portafilter on a flat surface, so you can start puck raking evenly so that the raking gesture will evenly distribute out the density within the basket.

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Here is a video showing the technique:

Step 4,  puck raking.

As you can see, there are some clumps in the basket, so we need to eliminate them with a puck rake.

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You need to use the puck rake to poke into the coffee ground just a little, around 1cm - 1.5cm depth, then you can make it spiral pattern movement from inward to outward, zig-zag, or as the illustration above, make a circle around the edge of the basket, the purpose of this is to evenly distribute the ground for better extraction.
So, whenever you see there is some higher or lower ground, just rake it evenly.

Mistake happens, what if my I’ve got an uneven coffee ground?

Coming back to this topic, sometimes we do overlook something, and it’s normal and there’s a way to solve this matter, as illustrated below, you can see the mountain is tall at the front portion, for this scenario, you’ll have to poke the puck rake down into the bottom and make a spiral, this gesture is to distribute out evenly from the bottom.

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Then slowly spiral up onto the surface and ensure the surface is distributed evenly.


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Step 5, a light tap.

Put the portafilter on a flat top then give it a light tap, a tap, or maximum tap it twice, so the ground will fall into the basket evenly.
Do note: do not tap many times, as this would lead to the high-density coffee puck then reflect on the extraction result.

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Step 6, clean off.

Whenever you see any coffee ground at the basket ring or ear, you can use your fingertip or a brush to brush it off, but do not disturb what is in the coffee puck.

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Step 7, tamping.

Then follow it with a tamp with a straight wrist, then with a twist to polish off the ground on top.

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Give Bugs Distribution Technique (BDT) a try.

By doing so, you need to catch the coffee ground from your grinder chute right at the edge of the basket and filling up circularly then leave the center slightly less dense (as illustrations above) until desired coffee dose.
After doing so, proceed with puck raking and distributing the surface portion evenly.
The reason why we have this BDT is that the normal flat even catching grinding builds up a little mountain right at the center, also it stacks up higher density in the center, which will lead to donut extraction.

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Above is the example of donut extraction, in which coffee flows out from the outer rim (this part is over-extracted) slowly flows out into the inner rim (this part under-extracted), eventually, it builds dry spots and flows out few tails, or sometimes the coffee spits and spills out, this is a good example of channeling.

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When the puck preparation is perfectly done, it will look like the illustration above with coffee dripping out evenly from each space, and of course, this hardly happens on the first day of doing puck prep, it takes patience, time, and repetitions to understand this.