M_Boats: Sail repairs

Hi everyone, I have been stumped trying to find the answer to this question. It seems simple enough. I must not be looking in the right places. Maybe one of you old salts out there knows. What kind of adhesive should be used on sail material? The sail numbers are peeling off my mainsail. It's an old sail, should be replaced, but I want to get one more summer out of it while I try out other sail setups and decide how I want a new one built. Any suggestions? Thanks, Larry