I actually just dampened the piece first and mistakenly referred to that as casing. After reading many board posts, I think I probably should have thinned the dye a bit and perhaps dampened the leather with alcohol rather than water. What's interesting is as it dried, much of the detail of the pyrography came back, not all, but enough. After totally dry I was able to go over the parts that were really faded with my burner and it worked fine. I still am unhappy with the finish and have already completed a seat for my tripod stool (not burned or embellished, just functional) so I won't be using it for the original project, but will use it for something else down the road, perhaps after figuring out how to improve the look of the dye job. Thanks everyone for your help!!