This is a very, very strong adhesive. If it sticks to a certain surface, it will probably last a hundred years. The reason I gave it a '3' is that it's not very forgiving of mistakes during setup and after a period of maybe 10-20 seconds the job is done and won't allow any further changes to the placement . There's also a weird white "garbage patch" that can form around the joint if the material to be bonded is glass - this has never happened before, but you can scrape it off carefully. I am not sure if I will take this glue again.