I made these two charts/pics as references for use while laying out PCBs:
Diameters of common thru hole cylindrical Electrolytic Capacitors
and Length and Breadths of SMD Tantalum Caps:
Notice that in thru hole electrolytic capacitors, the black band mark the negative terminals and in case of SMD tantalums, the black band marks the positive terminals. I learnt this the hard way - by soldering the tantalums the otherway round and watching them blow up. I wonder why some engineers make life so difficult for other engineers. How hard could it have been to follow the same standard on all kinds of polarized caps?