I'm not trying to harsh your mellow. I was just wondering what prompted the experiment. Now I wonder how much did the wax actually permeate the meer. Is the majority, or all of it, resting on the surface? The experiment simply stimulated my brain,
Even more questions arise. Does wax evaporate? Or is it simply abraded away through handling and buffing up a shine? Actually, the residues of the tobacco seep into the pores of the mineral and cease doing so when an opening is full or plugged. If the color is disappearing after a few bowls, I would posit that the disappearing color is the wax, not the deposits from the tobacco. I've never experienced color fading in a meer, for me it always darkens as the residues seep into the meer.
Until I see more than anecdotal evidence, I will stick with my anecdotal evidence that wax will provide a bit of color and such color is in fact superficial. The wax is providing the temporary hue. Tobacco coloring is permanent and comes from within the bowl. Surface wax merely protects the mineral and traps the residues under the shell. Without a wax coat the residues would seep out onto the surface of the bowl. Again, these are simple observations from many, fifty+, years of smoking meers almost exclusively in the evening hours.