A little chemistry lesson: the saponification reaction between potassium hydroxide (a strong base. Spell checker i my worst enema because it originally showed “string base”) and oils produces a liquid soluble soap and glycerin. Although liquid glycerin can be separated from the liquid soap it's more difficult and, as best I can determine, glycerin is not separated from the various Bronner's soaps.
Solid soaps are created through the saponification of oils with sodium hydroxide (think Drano) and it also produces liquid glycerin which is easier to separate from the solid soap. For me, the mass of liquid soap per liter, Bronner's soap produces a “harsher” reaction than Ivory soap. I assert that it's the glycerin content because of my familiarity with my rectum reaction to the glycerin/soap combination. My preferred concentration is 10 ml per liter or approximately 2 teaspoons per quart . It's strong, but not too strong.
As for “flavors" that I've tried:
Lavender produces a nice scented enema and expulsion assuming you like the scent of lavender. I do. And it makes a nice scented soap to bathe with (what? You can bathe with this? It's not just for enemas?).
Eucalyptus reminds me of Pine Sol scent. It produces an interesting warm sensation both flowing in and out. I've seen it mentioned as a possible punishment enema solution and from the standpoint of being a warm “burning” sensation, I understand why. What I found interesting was the scent of eucalyptus emanating from my skin the next day.
Tea Tree produces a nice warmth and tingling sensation in my rectum and Sigmoid. Not really a burning sensation but a sensation of warm stimulation. True of expulsion as well. I'm not sure how to describe the scent…maybe like a wet cedar aroma combined with a medicinal quality.
I have the unscented soap. I just haven't tried it yet.
And then there's the peppermint with its cool burning sensation. Like eucalyptus, I can smell the peppermint scent coming off my skin the next day.
All these soaps produces a nice milky color in water and do a nice job of softening and dissolving the stool contents of my colon for rather complete cleaning and rinsing.
A postscript: this morning I could smell the eucalyptus in my mask as I was riding the bus to work. It was a new mask and had no exposure to the Bronner's soap.