I'm still working through all your comments and messages, so here are a few more...

In this post, Back to Basics: Bath bombs, Vintage Blue asked: I have to say after trying so many recipe I absolutely love yours. Now I'd hate to mess with perfection but I gotta ask. If I wanted to add poly to this to help disperse the oils a bit more how do it calculate for that" And then if I wanted to add powdered milk, how do I adjust for that"

Vintage Blue wrote again after I answered the previous question: When adding the Natrasorb am I calculating 3% of the powdered ingredients or 3% of the entire recipe"

Thank you very much for your kind words about the recipe. I really like it, but I must warn those of you who live in more arid climates that this recipe is designed for where I live in British Columbia as it's really humid here. If you find these won't stick together, try a few spritzes of alcohol or witch hazel to bind them without setting off the fizz.
I don't recommend using milk in products like this as they are unpreserved and can go off in a matter of days. (Believe me, I know this from personal experience, and it smells just awful!!!) As using polysorbate in this, you could substitute it for a titch of the oils - ideally, we use polysorbates at 1:1 at least - and use it that way. 
For instance, I use 13 grams of oil in my recipe, so I would add about 13 grams of polysorbate 80 (possibly more, it's a try and see what works kind of situation),&n...