Is there ever a time when a kneadable eraser becomes so saturated with pencil/charcoal/etc that it no amount of kneading can refresh it, and it simple has to be thrown away?
In my experience it can. Whenever it leaves it's own mark instead of erasing the mark I need to erase I toss it! I like those white ones better, but it depends on the paper I'm using.
Good question. I don't really know. Mine have been going strong for a while now. I guess there is a time that it could, but you'd have to like... rub every possible part of it in charcoal or something, haha.
