Leather tannage doesn't really affect glueability unless the surface is coated with a finish. Vegtan is glued all the time for footwear and other crafts. Surface prep is the most important, I find that allowing the the glue to penetrate the leather first, then sanding it flat gives the most consistent gluing results. Also, thickness/type of glue plays a role.Chrome tanned tips are blue, vegetable tanned leather is not. Vegetable tanned leather, according to my leather craftsman buddy, does not adhere well with glue. I wonder if that explains the ubiquity of Elk Masters on house cues. Fewer popped off.