Okay, see, I'm still unsure of something. The Wikipedia article says that kind of smoke is, in fact, produced by burning something. But I'm not sure that could work for the Batman
props I'm talking about, which seemed to be self-contained, hand-held items, so it's hard to see how anything could be burning within them. Now, maybe when we saw, say, the Penguin's umbrella spew colored smoke, there was a hidden tube running to a smoke machine off-camera. But I'm not sure that's so. So I'm wondering if there might be some other way of producing something that looks like colored smoke, maybe something that's stored in a compressed-gas cartridge like the CO2 cylinders used in model rockets.