Thanks man!
It's not so much of a "dry" sponge I guess. What I use is an old kitchen sponge, and dampen it under the faucet with water. Squeeze the water out so much that the sponge is just soft and slightly damp. I pour some black dye into a paper plate, not a lot maybe a couple of table spoons. I just touch the sponge into the dye to draw up a little then pat an old rag to get the excess off. The sponge now is just barely loaded with some dye and I begin to pat the edges of the bag. I usually hold one end of the sponge and kind of slap it against the leather, changing angles as I go to keep a very random pattern.
I repeat this process a few times as I just try to build up the color. Too much black dye all at once won't look as good. It would look like you used the sponge as a rubber stamp and all you see is "sponge" pattern.
Once I get it to where I like it, I'll let the dye set for a few minutes. Then with a dry white rag I'll come back and rub off some areas. It kind of removes some black here and there on the high spots like around some of the stitching. Makes for a cool effect. Check out the bottom edge of this bag to see what I mean.
Thanks again!
Andy