One can mimic a tree using a thick paper towel and rolling it as a trunk. The role of the water and the rubbing alcohol in this experiment is that of a carrying liquid, because these liquids carry the ink up the coffee filter. The technical term for this is an eluant. The size of the original dot on the paper has no effect on the separation pattern, although the separation is better defined if the dot is smaller. The composition of the ink .
Different companies use different dyes to make their ink.
Some are doing it to produce special physical or visual effects, some are doing it so they cannot be accused of copying other people's product. The solubility of each component dye in the carrying liquid . If the dye is not soluble in the carrying liquid, it cannot be carried up the paper. This is the case of the permanent ink with water as the carrying liquid. Since most permanent ink are soluble somewhat in organic solvents, one can get it to produce a pattern using rubbing alcohol as the carrying liquid.