Throughout, we didn't have a clear description of the thickness of the grind. So when we talk about grinding, there will be a variety of different expressions, some people will use caster sugar to describe it, some people are used to using the scale size of the grinding equipment, and some people will use the sieve rate like Qianjie to express it. Although these methods have certain limitations, their ultimate goal is the same, to better understand the thickness of the ground coffee particles.
Scale referencing
This is the thickness parameter of the coffee ground that uses the scale value of the grinder, and generally uses the current popular and versatile grinder as a reference for description. For example, the 7 scale of the EK-43, the 26 grid of the C40, and so on.
It is a reference method with greater disadvantages, and the dazzling variety of grinders on the market makes buyers have a lower probability of holding the same model. The grinding value of different models is different, and the coffee ground will be different sizes of particles under the same scale grinder. When you have the same type of grinding equipment, because of its different installation, use, and maintenance status, it is difficult to use the same scale as a reference standard. If both parties hold different grinders, it will be more difficult to apply this reference method.
Visual analogy
The visual analogy is that we use some common objects to compare the grinding thickness of coffee grounds. Crude sugar and caster sugar are the most commonly used abrasive adjectives.
This kind of description can directly associate people with the thickness of the grind, but this is also a "not very reliable" way of description, because it is difficult for the human eye to distinguish the difference between small objects, and when our eyes are attracted to some objects in focus, it is easy to ignore other details.
For example, if you use a hand grinder to grind a finer portion of ground coffee, there will be more or less large-looking particles, and these particles will easily attract your attention and make you mistakenly think that this "coarse sugar" grind is actually the grind of "caster sugar" grains. Your eyes mislead your judgment, which invisibly increases the probability of error. Therefore, when preliminarily judging the grind, you can spread out the coffee powder and observe the whole to minimize the error rate.
Screen calibration method
This is the most common one in the front street article, and it is mainly used to calibrate cupping and judge the grind of hand punch thickness. Front Street uses a No. 20 standard screen with a hole diameter of 085mm。This screen is not used to sieve fine powder, but mainly to judge the grind.
Its advantage is that it is more reproducible, as long as the sieving rate is correct, different grinders can also find the same grind. The downside is that it's a bit of a waste.
The way to use it is to take 10g of coffee beans (or multiples of 10 for easy calculation, the more powder amount, the more accurate the data you get), pick a grind degree for grinding, then pour the ground coffee into the sieve, and shake it! Shake it horizontally from side to side!!
Shake until the pellets no longer fall off significantly (usually 3-5 minutes). The fallen particles are then weighed, and the sieving rate can be obtained by dividing the weight of the resulting powder by the total powder volume. 
Let's take a chestnut: we use 10g powder, the amount of powder is 8g, then the sieving rate is 80%, if we want to reach 90%, we can improve its sieving rate by adjusting the fine grinding.
Regardless of the reference method, the parameters given are ultimately designed to reduce trial and error in brewing new beans. For example, the size of the coarse sugar, or the 80% sieving rate of the sifted web, allows us to roughly adjust the grinding to the right range before brewing, which, combined with the speed of the water and the extraction time, ultimately consumes fewer beans to adjust the grinding parameters that best suit it.
end - Front Street Cafe.
No. 10, Baoan Front Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou City, Guangdong Province.