There are four main hand techniques that are used in iron palm.

Palm – the bag is struck with the palm.  In fighting this can be applied as a strike or a block.

Knife edge – the bag is struck with the outside edge of the hand.  In a fight this could also be used as a strike or also as a block

Back of the hand – the hand is dropped upside down onto the bag.  This is typically only going to be used in a few blocking techniques in a fight.  There aren’t too many strikes that involve the back of the hand as the bones on the back of the hand are brittle and close to the surface, so not only is it painful to be hit hard there, but it also wouldn’t make much sense to strike someone with it.

Fingertips – the fingertips are dropped onto the bag.  This is sometimes done with the fingers straight, or is also sometimes done with the fingertips bend and the hand in a tiger claw type position.  Care should be taken to be gentle with the fingertips, especially at first, so the bones of the fingers are not damaged.  In a fight, this would be used as a strike.  There are no blocks with the fingertips.

Sometimes the fist will also be trained as a part of “palm” training.  The student makes the hand into a fist and drops it downward onto the bag so that the front of the knuckles hit the bag.  This can also be trained on a hanging wall bag.  In a fight this would be used for punching.

Every school may have their own variation of striking techniques to develop.