Yeah - or if not actual 'Loctite', it'll be just some kind of generic thread-locker compound.

With actual Loctite-type stuff, like the blue one (low strength) that's commonly used on bikes, it's best to clean the bolt/nut with alcohol/naptha or whatever, apply the compound and then immediately thread it in and tighten to spec. It dries anerobically, i.e. with no oxygen, so will cure when the threads are engaged.