Earlier paintings by Tintoretto seem constructed with a more mainstream technique with a fuller palette. These are rather boring.
Many of his works can be seen at the following site:
http://www.kfki.hu/~arthp/html/t/tintoret/2religio/index.html
Starting with the 1560's, however, Tintoretto's works become more and more scumbling over a dark background. See Ascent to Calgary, 1566-67.
In many cases the backgrounds are visible through structures, like buildings, that should be opaque. For example