I mean, IIRC there was a thread dedicated for cast iron at one point.
PLUS INFINITY AND BEYOND. When I was doing the janitor gig, that stuff was awesome for spot cleaning carpets, and it’ll work in a bulk wet-cleaner, too.
Also this. Personally, for my carpets at home, I’m lazy about it, mostly because my long term goal is to rip the carpets out and put in “some form” of laminate flooring.