I use razor sharp ones right out of the package and use a piece of newspaper to show the sharpness ....and they are . After I cut the paper each one goes in my mouth one at a time .I have spent about 20 years working on this one and I have tried every gimmick out in magic land .... and the best place to do the dirty work is in your mouth ...hard but worh the work .

I once tested the razors were shar by cutting through a playing card and slicing the tip of my finger and blood was dripping all sown my arm. got a great applause though!!!!