I have a pool pump with a hard plastic body. I accidentally screwed the male part too far into the hole in the female coupler and the fittings are leaking. Guilty. So I looked for something that would actually seal the parts after reassembly. Unfortunately, after lubricating the parts with this thread sealant and letting them sit for a few hours, I came back and it was still leaking a bit. I ended up having to buy another brand that sealed it. I suspect that if I had never over-tightened the male fitting, maybe this sealant would have worked (I want to be honest). But in my case I needed a seal that would make up for my mistake.