As I have never added stearic acid to any soaps I have made, I don't know and cant really comment on it. I'f it was me Id just make a small batch to test It with a very small amount. You would have to talk to someone who has successfully made shaving soaps and has used stearic acid. I've done a couple of batches of shaving soap, but the results left allot to desire and I didn't bother perusing It any further. All the experience I have is with bath soaps and hand soaps, lotions and moisturisers.