Sharpness Testing

cerulean

cerulean

Joined
May 26, 1999
Messages
1,964
How do you test how sharp your blade is? Lately, I've been cutting strips out of a trash bag to test the edge. A very sharp blade will simply slide down through the material. A somewhat sharp blade will occasionally snag, although you still don't have to force it, and a dull blade will just tear the material.

I used to cut paper for testing, but I have heard (and believe) that modern papers contain abrasive materials that are not good for the edge.
 
Here are a couple of effective tests:

1. Put your knife in a slow-moving brook, edge upstream. Drop a lotus petal in the water and allow it to gently kiss the blade. If it parts without changing speed, your tool is sharp.

2. Cut your evening newspaper. The blade should slide with an even, non-vibrating feeling all the way down the page.

 
I've been using old business cards, but that's probably not the best thing to use.

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Run the edge over the tops of your arm hairs, not touching the skin. If the knife is REALLY sharp it'll slice the tops of the hairs. I've never gotten my knives this sharp but Joe T. has done it with his Calypso Jr.

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Johnny
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I like this one I read in Dee Griffin's(the Dead Cow Doctor)paper:
http://gpvec.unl.edu/public/files/feedlot/sharp1.htm

Hold a pen vertically, place the blade edge against the pen. The higher you can turn the back of the blade up befor the edge slips the sharper the knife is.

His paper has nice graphics that describe this and the entire sharpening article was very informative.

-j-
 
After sharpening, you clean a salmon with it. Put the fish back into the water, and it swims for several miles before realizing its backbone has been removed.
 
STUPID ME!!!!!! AM I THE ONLY MAKER WALKING AROUND WITH A BARE NAKED LEFT ARM??????????

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"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
 
L6S you are not alone!! I have tried to keep some hair on my arm but the result is probably worse than naked arm. It looks as I have some nasty skin disease in my arm. I have moved to my left leg. Before christmas I'll have smoother legs than my girlfriend
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.

A good way to test sharpness is to cut free hanging toilet paper or kleenex
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. Not as much bulking agents as in normal paper...
Try to make a clean cut horizontaly more than 20 cm below hanging point, 10 cm above the end. If you can do THAT... WOWW!! I have newer been succesful. --> Back to shaving
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!



[This message has been edited by Tommi (edited 13 October 1999).]
 
I love the hair test. While at work the other night I shaved all of the hair off my left hand with my mini Copperlock (it gets kind of boring during night shift). I also like to remove the skin off of a ripe tomato.

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The only substitute for good manners is fast reflexes!
 
I like the hair test and the trash bag test myself.
I will have to try the lotus petal trick when I get my Sebenza. I hear they are wicked sharp right out of the box.
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The greatest thought that has ever entered my mind is that one day I will have to stand before a Holy God and give an account of my life.
*Daniel Webster

Rev 20:12

 
I always test the blade on my thumb. If i can see it digging into the skin without moving the blade, i know it's sharp. Not exactly the safest way to check...


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"If you fake the Funk, your nose will grow."
- W. Bootsy Collins

 
Tommi, somehow I knew that you would reply after what L6STEEL said
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I'm pretty much trying to avoid the 'spotty left arm'... maybe I should shave more
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The 'free hanging toilet paper' -test! It's tough. The paper is so light (bends before knife bites in) and seems to tear easily - but clean cut is hard to produce. Doesn't matter much what brand you use, they all seem to be as hard to cut. I think polished edge is the best here. Come on, guys! What do you do with all the knives you carry in your pockets while you are sitting in the toilet?!?
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Hugo
 
With all the fascination we have for seeing how vorpal our blades are, I couldn't resist recently picking up a Razor Edge Tester.

Though a bit pricey at $7.95, it is actually a useful means of checking both edge sharpness as well as smoothness.

Most of the tests can be adequately done with a "bic" pen, but the ends of the tester are flared, making it easier and more accurate in terms of picking up microscopic nicks/imperfections in the blade edge.

I like it, and it's yet another gadget to go into my evergrowing cutlery arsenal.
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Blues

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Live Free or Die

 
Please, please, please - be careful with your knives when sitting on the toilet. If you should cut your hand (or something else) by accident, it would be quite embarrasing to explain at the emergency room! Personally, I would LIE
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Sorry, I just couldn't resist!

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The only substitute for good manners is fast reflexes!
 
It's comforting to be in the company of people that understand certain things. Left forearm is bare, legs are slick (envy of my wife!)and currently working on my belly. Is there no salvation to this never ending pursuit of the hair-popping blade? By the time someone finds it, I'll be SLEEK!
 
The best excuse for lack of body hair is to join a swimming team. Then you're even entitled to shave the top of your head.

Almost any kind of paper has some clay and grit in it. I usually don't do too much edge testing using paper anymore. Newspaper is a pretty good test since it is thin.

The obvious thing for a man to shave is his face. Just grow a couple days of stubble, lather and shave. It is humbling to compare a $.49 Bic razor to your $200 super steel pride and joy. Be careful or you'll get a razor burn.
 
Usually if it looks sharp, using a bright light and a loupe, it is. As a result of some testing for another thread I found that cleanly slicing off a piece newsprint rolled into about a 4 inch tube of about 1 1/2 layers took a sharp knife.
 
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