Man, you don't put that stuff on with a brush! Dip a small piece of Tee shirt in the dye, just enough to wet it and wipe it on the bamboo. This stuff dries really fast so give it a few minutes and wipe it again and again until you get the coverage and darkness you want.
Another tip, the edges of the bamboo will absorb the dye at a much higher rate than the back. To keep from having overly dark edges I run a piece of Tee shirt with tru-oil down the edges and let it dry to prevent this excess absorption. The edges will still absorb a little dye but at about the same rate as the back.
I use Try-oil on my bamboo backed bows, it is compatible with leather dye as is the epoxy acetone finish(massey).
Leather dye rubbed on with a piece of Tee shirt and finished with Tru-oil;