| The stuff can usually be rubbed off with your fingertip, it's kinda like a rubber cement. If necessary, use a very small amount of solvent on a q-tip and then rub off with your finger, don't get the solvent around the edges or it could affect the bond of the top and bottom section of the transducer.
You're best off using the original stuff K&K makes and supplies, it's very thin and give the best pickup to bridge contact, short of super gluing it. I'm a longtime K&K Dealer, email me your name/address and I'll put a piece in an envelope to you. | 
