I’ve got a clogged sink, and have been reading the labels on a bunch of different products lately. I’d always assumed that they were a strong acid of sorts, which would dissolve whatever sort of material was built up in the pipes. But I’ve noticed that a lot of these products specify that they’re non-corrosive, so I’m not sure what other sort of mechanism may be at play here.
A lot of these use strong bases, like sodium hydroxide, that will dissolve fats and proteins but leave most metals and plastics unharmed. (except aluminum)
You’re correct, and that’s why sometimes they work really well and sometimes they make the problem much worse and profoundly annoy the plumber you’ll eventually call to fix the issue.
A strong base + lipids stuck together in a pipe means a solid block of soap after a while, sometimes too big and clogged to be effectively rinsed with water, meaning you just made the blockage worse.