I use several types of finishes, one I choose to use on the inside of the call is CA thin glue, this seals and protects the inside from moisture. I also use a friction polish called Shellawax, it is from Australia, expensive, but if used right and allowed to cure it finishes a trumpet with a nice sheen not too glossy and will protect the outer layers against humid conditions. It takes three weeks to cure properly, so if you choose this polish take this in consideration before selling or giving one to a hunter. I also use lacquer based finishes on some calls, those that require time to cure, because the longer the cure time the more intense the seal....quick cures are for looks, sealing very little, always consider the calls possible enviorment when choosing your finishes.