I have been that when applying Balsa sheets to the bottom of the. wing paint the ribs and any place of contact on the wing and balsa. witl Tight Bond glueThen let them dry. The next day you start to iron the balsa to the wing with an iron. The heat will activate the tight bond an it will adhere the balsato any point of contact between the sheeting and frame. This way you can be the sheeting is glue to the greatist area. Is a god idea.