Hello Jim,
I in no way consider myself an expert on the topic, but since I saw that you did'nt have any replys yet , I thought I would throw my two cents in, so here goes.  I suspect that those white funnel bands are division markings. I've seen photos with one , two, and even three bands on various classes and some without any at all. You will also see something like this on some, but not all of their cruiser funnels. You will also notice large japanese characters on the hulls of certain IJN destroyers and again I think this identified their divisions or possibly as assignment as escorts. Keep the wet side down....