Let me try to explain.
My camper trailer has a frame piece, its a rectangle tube, and it has an end cap welded to cover the opening at the end. Its welded at the top and bottom, not the sides. On the sides there is a bit of a gap. Id like to seal up. I was thinking an expoxy or something similar.
What would you use in this application? I need it to be black in color. Is there a good caulking that bonds, dries hard?