Grind size is an important consideration when conducting either CO2 extraction or ethanol extraction. Grind size may be important for different reasons however, depending on the extraction method.  Here are some key details for that are important for grind size:
The grind size is  small with CO2 extraction so that more materials can be packed into the column. A small particle size wheel packs more efficiently into the column and  thereby prevents channeling within the column.
Improved mass transfer is the second reason a small grind size is desirable.The larger the particle size, the longer the cannabinoid will take to diffuse out of the particle and into the flowing stream.The smaller the particle size the better the Mass transfer will be and the shorter the time the cannabinoid will take to diffuse out of the particle.. This is true for both ethanol and CO2 extraction. One important aspect of grind size is particle size distribution. Four particles of all the same size, extraction is more uniform. or a mixture of very small particles and large particles, a small particle will be extracted before the large particles. those small particles then begin and start you over extract.