Hello all, this is my first post I am new to this site. I just want to say this site is great and the people here seem very friendly.

Now to the point. I have recently been explain an "Iron Claw" technique. The training method is to actually rip tear and crush tree bark with your bare hands to eventually harden your hand to rip flesh (not my intention). But i would like to know, has anyone practiced/mastered this technique? What training advice could u give me? Have u ever had to use it in actual combat?

I read somewhere that Ninjas in old times would practice this art. Thanks in advance