RE: Spray can insulating foam for structural support under turtle back
The "original" Gorilla glue was intended to replace white or yellow glue for wood working. It is activated by moisture [when using you wet one part and apply the glue to the other then attach and clamp]. When it is setting up, it expands and some usually oozes out in the form of foam. It works very well on mortice and tennon joints.
Gary