It takes hair a while to acclimate to using soap/shampoo bars (only difference is that one is considered "super fatted.) It should feel fine after using your rinse out conditioner.

I have moderately hard water--3 out of 4 when setting up the espresso machine, LOL. If you're still feeling the soap residue after using your rinse out, I'd suggest that you try a different rinse out. (I use really rich products, but felt the Jessicurl made my hair limp and lifeless in a week.) If you have really hard water, you may want to try a final rinse with distilled water (regardless of whether or not you're using soap bars.)

Castor oil is usually what makes a soap bar lather. It's also one of the few ingredients that make my hair frizz and tangle. For anyone considering using natural soap bars for hair, try one without castor oil before making up your mind about them.
3a (Corkicelli), highlighted, fine, low porosity

HGs: Anything Sevi; Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; UFD Curly Magic; Botanical Spirits Jellies, CJ Repair Me, Aloe Fix