Yeah the sharpie is just for reference.
I have my own small kiln which allows me to develop my own techniques.
Basically its a modification of Raku
if you look at the pics where they pot the pot in paper or whatever thats what I do, the burning makes all kinds of earthy colors on the clay.
One could probably do the same after the fact by burying the pots in a pile of leaves and lighting it on fire, I think.