I'm a virgin when it comes to using bamboo for a backing. But I picked up a couple pieces at MOJAM last year and am wanting to try my hand at it. I have a pretty piece of mulberry that was too knotty to leave unbacked. However the piece is slightly reflexed and I want to keep it in the finished bow. My question is, if I wanted to do any more heat warping do I have to do it before I laminate the boo backing on? Or can I do that after the two pieces are together?