clay

So I'm pretty new to bonsai. I have a few trees that are bonsais in the making and I'm just starting to get a little more experimental. This is something I was going to try as a soil component. It's stoneware clay fired to bisque temperature so it will absorb water. Any thoughts on what else to...

I have been experimenting with terra cotta lately. I have performed numerous tests using varying dry/wet filtration methods relying mostly on particulate sizes and impurity concentrations of clay from different areas.

Can anyone ID the maker of this pot?