Can smooth rubber be made grippable? As in the case of a cell phone case?

I have a silicone cell phone case that in my opinion is too smooth. Are there any chemical augmentations that can be done to the case to make the rubber feel less smooth ( without damaging the material that is)Can smooth rubber be made grippable? As in the case of a cell phone case?
brush a LIGHT amount of mineral oil (available at walmart or hardware store) on it. let it dry at least an hour, make sure you only put it on rubber.


if its not sticky enough try another LIGHT coat, dry 1 hr, repeat as neccessary.Can smooth rubber be made grippable? As in the case of a cell phone case?
3M spray n stick.