I think part of the difficulty in figuring out how to use TD/how much to use is (a) how it is used, ie; to color the whole batch rather than in swirl amounts and (b) the fact that people differ in terms of how they measure, ie; "x" amount ppo/dry rather than "x" amt ppo pre-mixed in oil. Ugh, so I am probably going to describe my own usage incorrectly, my math is horrible.
For my own measurements, if this makes the measuring differences more clear. I almost never use TD in the whole batch, just in a separate color batchlet for a swirl, so assessing a ppo measure to which to add TD would not be useful for me, it is already in batter form when I add the TD to the part that I want to be white for a swirl.
My TD powder (the Nurture/ss.net combo) is mixed at 1 tspn mixed powders:1 TB SAO.
So my rough estimate of 1-2 tspns of the masterbatched TD/SAO mix per cup of soap batter (for the white swirl amount) would roughly break down into 1/5 - 2/5 of a tspn of powdered TD, mixed into 1/5-2/5 a TB of SAO oil per *cup* of batter.
I think. Although I am so confused I kind of have no idea anymore. LCW, I really like the milkiness of the Nurture TD, but after several batches using different water amounts and mixing it in different ways I gave up on it using it alone, I experience glycerin rivers in pretty much all of them. Perhaps it was my oil mix/water amount/location (ambient temps)/process, so many things go into this.
I am not opposed to glycerine rivers in principal, but I want to choose for them to appear, if at all possible, so the mix w/the of Nurture and ss.net TD powders works well for me, I am willing to give up on the clarity of the white to be able to reduce the chance of the rivers.
I am sure my math is wrong above, but I am going to eat lunch now, that is way more fun than math.
Just for me and with my formula and process (I am so anal that despite the foregoing, I am not willing to totally recalibrate everything in those things to get them squared up with the Nurture TD, it is easier the other way