This is what mathematicians do when they're bored. I wouldn't swear in court that there are no mistakes here, but this is my first stab at a theoretical approach to spine taping.
Suppose a razor comes out of the factory with height h[0], grind angle 2*theta[0], and thickness 2*t. Because we always hone it with tape on the spine, t does not change, so the razor is ground away to height h[1] and angle 2*theta[1].