Originally Posted by unworthy1

I thought you were looking for a water-clear shellac, but even the most "blond" shellac is not that clear: there's a bit of yellow in it. But there are plenty of white-pigmented shellacs in your LHS: Zinser and Bullseye make some. They are advertised as "stain killing" primers, but what they are is shellac with titanium dioxide (AKA Titanium White pigment). That will keep a white cloth bar tape white.