Different inks can be used to distress (i,e., age) commercial fabrics, make spray patterns, marble fabrics, create a dyed effect, color in a stamped or printed image, all sorts of things. And if you want it a bit thicker, just add fabric medium. They do need to be heat set between colors to prevent bleeding or blending, and as a last step to make them permanent and washable (the distress inks are not permanent, nor are the metallic or pearlescent inks).
Another trick is to use fabric markers as a resist. Outline a shape or form with the marker and then heat set it. You can then paint inside the marker lines with the ink. Heat set when all done to make the ink permanent and washable. Both Liquitex and Tsukineko inks are highly rated in addition to the Daler-Rowney.
I haven't dared try them on my limited supply of silk yet, so I'm eager to hear how that goes for you!