Mineral Ink oil is clearly split into two groups based on their viscosity difference: petroleum solvent with low viscosity and ink oil with high viscosity。
Mineral ink oil grade with distillate range of over 320 ℃ (crude oil vacuum distillates, including so called machine oil ) could have a wide viscosity range from 20 plus to several thousand mm2/s at 40 ℃ dynamitic viscosity; only the light viscous ink oil with less than 100 mm2/s viscosity is used in Chinese printing ink formulation
High viscosity impairs ink oil functions to efficiently solute resin and to quickly be released in paper, which is a least attractive ink oil attribute
Lower viscous ink oil basically is able to solute more resin which guarantee firmer and polisher printing
Printing ink viscosity is mainly controlled by resin instead of ink oil. Ink oil, high or light viscous, should be absorbed in paper and eventually be volatilized in printing process; black fingers from reading newspaper are largely caused by inferior resin and an improved binder formulation can overcome the problem.