I use 6% and my CO is 40% but zI have very oily skin and very hard water and very low humidity. Each formula will be different for not only each person but for differnt types of soap like milk, veggi, AO or salt.
I usually sf at 8%. But that's because going any lower with a recipe with coconut oil will dry my skin out a bit. Now, if it's a salt coconut oil bar, then I sf at 25-30%.
I don't change the sf % when I use milk or purees in my soap.
I'm new so I have stuck to 5% until yesterday. I made a batch with 30% coconut and did a 9% SF, which was just a shot in the dark. Hope it turns out ok. :???:
I have been trying a superfat of 7%, but I might increase it to 8%. I am new still and I think having a wider margin of error, especially in smaller batches of soap, is a wise thing. I might also be overcompensating for my first batch being lye heavy though... So, still debating if I should go to 8% or stay at 7%