we've used the Sureflex line from
www.ColorPlus.com . They have a water based dye that doesn't clog up the pores so you can still use conditioner on your leather to keep it soft. We used the dye on a naugahyde backdrop for video production work, and I purposely tried to scratch it off after it had dried. It had no loss of color, and showed no damage whatsoever. I'd recommend the stuff.
