Check out scrubber pads here as a start. [snip a sensible
alternative non specialized generic thing that works just
as well].

On this subject, I was amusing myself searching around about
bentonite clay. Okay, so I retract my prior sarcastic remark
about it, seems I was all washed up there.

But here's the funny part. So here I am, searching for bentonite
clay, and I discover that they sell it as a mineral supplement
to humans for like $20 a bottle.

Then I think, what's the cheapest way to get this stuff?

Quarries, of course, but forgetting that, as another poster
pointed out, Special Kitty cat litter, 100% pure bentonite clay.

So basically the marketeers are ingenious. They found a way
to feed kitty litter to human beings while increasing the price
by a good 50 times.

You have to give them credit!

C//