I was wondering if anybody here has heard of the following test of sharpness for blades. I use it often for knife sharpening and learned it from the Murray Carter video. Murray is a knife maker and sharpener extraordinaire. In his video he decribes a method for testing an edge whereby you press three fingers held closely together against the edge with your thumb on the spine. You then proceed to move your fingers slightly along the edge. That's right, I said along the edge. The three fingers gives a large surface area and instant feedback to your brain. Anything but a perfectly sharp instrument will glide uselessly along your fingers with no tension or breakage. A sharp knife will give a tiny tug when you start to pull and your brain will know that any further movement will cut you. It's an excellent way to feel that toothy edge. The thought of this usually makes people queazy if they are not familiar with it. I think I might try it out on razors.

This test is discussed in depth on his DVD and I am in no way giving the complete instructions here. I would highly recommend you seek the complete text or view the film prior to using this method unless you are completely comfortable with the idea.