What is/How to Alum block?

OK, I don't feel like a newbie anymore but will concede that this is a newbie question.

I understand that Alum block is used to reduce or eliminate irritation after shaving. But, as I've never read or seen how it is applied, how is it applied? Do you just rub it on your face or what?

Also, exactly what's going on when it's applied; i.e., How does it work?

Thanks in advance.

search and you shall find!
http://straightrazorpalace.com/shavi...lock-tips.html

Have you heard of the expression "rubbing salt on a wound?"
That's it.:D
You rub it on your face while it's still wet. Areas that were irritated by the shave will sting. It's supposed to help close pores and to have an antibacterial effect.

Basically, leave your face wet after a cold water splash, wet the alum block, and give your face a pass over with the alum block.

Lets you know any areas you may have pressed too hard. :P

I have used an Alum block for many years. It is a crystal-like stone that you moisten with water and gently rub on your face. It acts as an antiseptic for razor burn and will help to stop bleeding of nicks and cuts.In addition to the antiseptic properties it also acts as a balm. A styptic pencil which is specifically used for cuts and nicks is made from alum block crystal that is powdered and concentrated into a stick.

A