How many thermocouples do you have?
I've no clue where to start with experimenting here.
There is some good understanding of this by explaining my single fire since it essentially combines the actions of a bisque and a glaze fire in one.
It ends up being 100F/hour for 20 hours, with a give or take -+20F/hour that gets me to 2200F, where my top is cone 10 and bottom cone 6.
Due to this temp differential, which should be learned in your kiln with cones on every shelf, it's impossible to go any faster because after going slow for water smoking, I gotta go slow through the dunt range of 473F, then, slow for quartz inversion 1000F, then slow for burnout 8 hours with a lot of oxygen to 1900F, then reduction makes it rise slow to finish, so at every turn to gain speed it's just like...eff it. And everything comes out perfect.
There is a Washington Street Studios video that goes over the melt, boil, and vapor times of different materials. All of which need to go slow through there overlapping times, which includes the times their different phases interact with each other.
So going slower than slow, always turns out a better product.
The reason I don't like 2 firings, is because you can't really make either faster, or it severely limits the materials you can use, because the clay body(bisque), and glaze in the glaze fire, both want to go slow AF to produce the strongest, most cohesive melt. So you end up basically using twice as much energy no matter what, or limiting your materials, or churning out meh if you don't limit materials.
Extremes...
A kiln with a 2 material porcelain only. (2 materials)
A kiln with 4 clay bodies and 10 glazes. (40 materials.)
I recently took that dark manganese body that "bloats at cone 6" to cone 8 and it came out fine.
It's no different than a pot of water overflowing if you boil to fast.
Sorce
