These leather dyes are meant for undyed vegetable tanned tooling leather and not for redyeing products that have already been colored.
I decided to go non-flammable for my first attempt at dying leather (veg tanned). It went on easily and I was able to get pretty uniform and deep color. I followed with a conditioner of pine pitch, mink oil, and beeswax. This appears to have sealed the color well also.
BLACK DYE HAD GOOD 1 COAT COVERAGE, I USED 3 COATS TO SOAK IT IN... IT ACCEPTED BALM EASILY. SNO SEAL ON TOP AND IT WAS A GREAT PLIABLE GUITAR STRAP