Maybe the baking soda breaks down
I bet if I used West System 404 filler it may last forever
Hank
Been using West System since the early 70's built and repaired many boats with it and have used it on many other projects.....picked up a gallon and hardener never opened at a garage sale last summer $5 for both.....
One of the fillers made by the West System looks just like baking soda....but is fiberglass.....
