I did not put anything for the first few flights. I crashed my plane but it was not because of the wing. I then put nylon cloth on top of the joint. It is like fiberglass but not as good I think. There was no fiberglass availble at the time. Since mine came covered I just put it on top. Its a trainer it does not have to look good. It is sticking on the wood a little where the servo slot is. But the rest is on the monokote.