Hand Grip Surface

[farm1810]

I have a set of Venture passenger hand holds on my RSTD. I'm getting ready to take a crack at a quick release trunk mount, but don't want to lose some form of hand grip for my passenger. Making the bracket / hand hold bar is no big issue, but what do people use for some form of non slip surface? I have seen the material for tools that you dip the handles of pliers (for example) into it. And, I have seen truck bed liner material in a can. Has anyone tried either of these for hand holds on a bike?