Here's a video from our buddy Miles - Homer & Cristina demo'ing some volcada technique/vocabulary. In spite of Homer's "ever so slight" nuevo-esque stylistic influences, their volcadas look like the real deal. I have no doubt that Homer falls in the class of "good", or even "great" tango teachers.
They even do one that I have in my bag of tricks but had forgotten about - I'll call it the "volcadafollowedbyadoublepivotingcalesitaresultinginawoundupcontratensionreleaseintoanothervolcada" or perhaps the double pivoting double volcada. Whatever.
Also note that you can lead a volcada at almost any point the woman's leg is free (from a pause/stop obviously). A cool version is to get one as she unwinds out of the cross on the close side. Always a nice little surprise for her.
Note that the juiciest volcadas are tiny, milonguero volcadas - languid (my new favorite word 8) ), lush, sweeping, juicy - fluid. At least that's the feedback I've always gotten from mine.
Again, don't try this at home without some good instruction. Try as you might, you won't learn it from these videos, and you could endanger/injure her lower back.
By the way, the song is "Sin Rumbo Fijo"... sung by Ángel Vargas... Orquestra Tipica Victor... recorded in 1938...