causeitflies

Over the years I've used the expanding foam to fix many wings and always have some in the shop. With my older gassers with foam core wings the smoke fluid and gasoline would eventually seep into the wing and dissolve the foam. It comes with a tube applicator but you can extend it to reach far into the wing. I usually buy the "super expanding" variety but they also sell medium and low expanding versions. It's the same thing as the polyurathane Elmers or Gorilla glue. As a matter of fact, years ago they also advertised it as insulating foam AND/OR glue in one can.

As long as it has somewhere to escape it won't bulge the wing and it foams quickly so it won't have you guessing if you've used too much. Use acetone for cleanup and it CAN get messy. Once you use it you may as well go around the house and fill all the gaps because it will only last a month or two on the shelf if you're lucky.