I've been working on my cupping technique lately and have found some helpful advice on grips by scanning through the forum archives. But I'm wondering about the bottom of the harp. Brian Purdy's demonstration (http://www.harpgear.com/atone.html) shows a full seal on the cheeks and chin. I'm having a lot of difficulty getting this seal: any advice on how to do it or how essential it is? I feel like no matter how much I seal up the sides and the back, air is always escaping by my chin.
