Feldspar in Clay
I blend these clays without any feldspar addition to the body so that the body stays open, even at its peak temp at cone 10.
I find this helps the pot to breathe more, it has a softness to it. I find the commercially made clay bodies that are loaded with feldspar are tight, they have reached a maturation point, a vitrification that makes them almost glass-like and I find clay like that doesn`t communicate its raw state to me; it`s been processed too far and something is lost in the in the firing process.
I will not use feldspar unless I absolutely have to; for example if the glaze is spitting. I learned this from using Japanese pots, they sound different; if you tap them, they typically go thunk thunk, whereas a pot made here will typically go ting ting.