Stag is wonderful for things like welsh plugs... I also recently put a tiny bit of it on a dog's nose, and it wouldn't stop licking it all afternoon! It says on the tube that it's safe for food... hmmm...

I've been using Loctite 569 (in the red tube) for ages and have always been happy with it. I started using it because it's what's used for LPG fittings, and then started using it for petrol, oil, hydraulics, water, etc. etc. and have always found it good.