When I was planning the kiln, I looked everywhere and asked everyone this question: Can you bisque in a soda kiln? As an answer I got the same thought that had already occurred to me: You might get fuming on the ware that interferes with how the piece accepts glaze. I went ahead & built the soda kiln anyway, because a) my old kiln was about ready to fall down, so I had to do something; and b) if it turned out that the soda kiln was inappropriate for bisquing, I could always buy an electric - a readily available (if expensive) solution. But I am now in a position to answer: The soda kiln can double as the bisque kiln. I have observed some minimal fuming; a few pieces appear a bit darker in spots, as if they've been lightly toasted. But I have not noticed any difference in glaze application. So, mystery solved. If you are pondering, consider this question answered.
Not that I have any reason to do so, but I could probably diminish the fuming even further by scooping the remnants of the soda salad out of the burner troughs.
Architectural Digest profile of East Fork Pottery
39 minutes ago