The soaping effect is defined as "an undesired foaming phenomenon observed in skin creams formulated with soap based emulsifiers". You may have noticed this in your lotions - the white streaks when you rub the lotion on and a slight tacky feeling on your skin.
Why does this happen? It's saponification!
The fatty acids in the lotion, combined with an alkaline ingredient like triethanolamine or potassium hydroxide, create a soap, which acts as the emulsifier in your lotion. (A common combination is triethanolamine and stearic acid.) If you're using a stearate or oleate based emulsifier, you are bringing the water and oil together in your lotion by creating a soap, which is going to leave those white streaks when you apply it.
What can stop the dreading soaping effect?
- Adding dimethicone at 2 to 3%.
- Using a non-ionic emulsifier like Polawax or emulsifying wax NF.
- Using a cationic emulsifier like BTMS.
If you don't want to use silicones, then your only option is to change emulsifiers and see if that helps.