A query for the craft-minded

In my newfound fascination with tie-dying, I find I’m getting to that point in a new hobby when one has enough rudimentary skill with the process to start thinking of new stuff to try.

For instance: what would happen if I took a pair of stiff blue jeans of dark blue denim and, after tying them in various ways, dipped them into a strong solution of bleach and water? Would this result in a kind of “negative” effect on the jeans? Would the same occur if I did this with a heavy black sweatshirt? And is it possible to tie-dye a down comforter?

(I’m not serious about the down comforter. But the bleach idea intrigues me.)