Just tore down my second carto I had been using for ~3-4 days. Same results as my earlier picture, unfortunately.
I also made sure to keep it moist at all times, too. Doesn't seem to have helped.
Oh well. I guess we just need to look at these as a fill once, maybe twice, piece of equipment, then toss. After all, that's what they're supposed to be.

Heck at $2/carto, even using one for a day, then tossing it is still cheaper than analogs!
That being said, mine are more "scorched" than flat-out burned through. I'm wondering if it's getting hot enough to discolor it, but not really burn it. I'd be willing to guess that, even though these are scorching, they're probably producing hardly any particulates from the polyfill. IMO, not a whole lot to be worried about, especially when you considered all the tar and crap you used to get from analogs... these are probably still orders of magnitude less bad for you.