Generally speaking, cotton is good, and silk cotton is the best. Cotton will dry up if it is not used for a long time, and will break when it is used, resulting in broken foam, which will affect the use effect of writing brush.
The cotton in the pen container is used to store ink.
If it is not in the ink box, the ink will easily thicken and dry, which will affect the use effect of the brush, and the ink box is also difficult to clean. It can absorb ink and store it.