silverstarling

A very common complaint! I have a bowlback and am far from expert, but it will become a bit less slippery over time, meaning that your grip / grasp / clasp / bear-hug will eventually bring it under control, with experience. And with surprisingly little effort or strength involved. It's mostly a feel & balance thing, like learning to ride a 2-wheel bicycle... it's really easy after you know how, and you'll only know how by feeling it. You bet that mine, at first, felt like a slippery watermelon seed!

I took a clinic on Italian folk tunes two summers ago here in NJ, and the instructor, John LaBarbera, could just hold it up to his chest, while standing & walking, and play with total fluidity & speed - and no anti-slip equipment! He just sort of clamped the end of the body under his picking-hand wrist, held the neck & fretted with the other hand, and played.

Try a chamois cloth. It shouldn't mar your finish.

Great solution is to go to any large home improvement or department store and get a small carpet pad. It is gummy and you just lay it like a cloth on your lap and end of problem. I even have an old useless but very pretty bowl-back mando-cello, on display on a shelf. I park it on a piece of rug pad so it won't slip. Works fine. good luck.