Grind
If u are planning on grinding the beans yourself then do not atemp to use the centrifugal normal grinder at home - That pulverizes the coffee and almost always results in uneven particle sizes.
2. Choice of the grind size based on the type of machine you are using for extraction – The choice of grind is also dependent upon the machine you are using. Few like the espresso machines put in excess of 10 bar of pressure to they brew and their extraction time is barely 20-30 seconds. The grind in this case demands to be fine which exposes more surface area to the water and easy extraction is facilitated.
The Coffee Grinds also have to be used quickly after grinding. There are many volatile compounds in coffee and grinding increase the surface area of coffee allowing easy escape of these. The coffee slowly oxidizes and starts becoming sour.
15 Mins is the time before which coffee grounds have to be used
4 Weeks is the time before which roasted coffee bean has to be ground and used
That’s the tech behind grind time