[WARNING: probably more than you want to know] True horn (that made of keratin - essentially compressed hair) can be quite an unstable material on knives intended to be used - especially in thin sections like pocketknife scales (which are also exposed to a lot of moisture variation on a daily basis in use). Trying to stabilize true horn scales is pretty random - often the horn will curl and distort severely while being stabilized, and even after stabilization will continue to move. (I once got the idea of recreating the gorgeous bias cut cow horn seen on some early Sheffield knives and getting it stabilized, but talking with several stabilization experts soon cured me of the idea.) Quite a number of custom makers have sworn off of using any type of true horn. Also note that certain beetles absolutely *love* to eat horn.