Easy / best test for knife sharpness?

[rt014]

What is the easiest household test that one could use to judge subtle differences in knife sharpness?

Thanks

 

[Possum]

Howdy there..!
I usaully check my knife edges the same way I check fishing hooks. I take the edge slide it from the back to the front of my thumb nail and if it catches the surface of the nail it is sharp enough. Or you can test cut a thin sheet of paper as in a magazine page, if you cut hold it up and slice throught it your blade is sharp. Good Luck and Be careful...!
"Possum"

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Thomas Clegg

 

[The General]

If you can shave arm hair and cut a bit of paper 'flat' on a cutting board in half, erm I mean if you can shave a bit of paper that is flat on a board and in effect have two bits of paper, without going through to the otherside of that paper, then THAT is sharp.

Or to put it another way, can you get the paper on a flat surface to 'curl' up as if you were using a chisel on some wood, without going through the paper, then you have a very very sharp knife.

------------------
Wayne.
"To strive to seek to find and not to yield"
Tennyson
Ranger motto

A few useful details on UK laws and some nice reviews!
http://members.aol.com/knivesuk/
Certified steel snob!

 

[Raptor]

Actually, Possum has hit the mark for a good way to test both sharpness and edge geometry.

I hold my thumb at about a 45deg. angle and place the sharpened edge in the middle of my thumbnail. Then I slowly tilt the spine of the knife back towards the 45 deg angle of my thumb. The edge will eventually slip. This indicates the approximate geometry (or angle) of the primary edge. Be sure to check along the entire length of the edge using this method. You can use this information, if you wish, to add a sharper edge by reprofiling the blade to a steeper angle. I have found that if I perform this test and then re-sharpen the secondary edge first followed by the primary edge followed by a steeling and then stropping that I can almost always increase the angle of tilt before the knife slips from my thumbnail. I find this to be a good thing. This will result in a slightly thinner edge but also a slightly sharper edge. I guess that it all depends on whats more important to you.

As for what else is good around the house for testing an edge. I usually choose plain white printer paper and I also implement "the free hanging toilet paper test".

--The Raptor--

[This message has been edited by Raptor (edited 06-21-2001).]

 

[swede79]

Try shaving your face. All of it. Especially when you're late for work. If you think twice about using your knife, it's not sharp.

 

[Nakano 2]

The S.G. method is the quickest and a good indicator. Careful if you have a crew cut!

Nakano

 

[OwenM]

The toilet paper test is great, just don't let anyone who doesn't "know" you catch you doing it. They'll think you've lost your mind

Notebook paper is always fun. You can pushcut it, slice it, filet it, "shrimp shish-kabob, shrimp salad, shrimp sandwich, and...well that's about it".
Sorry, I watched Forrest Gump again today.

 

[Mitchell Knives]

I do the thumbnail test, filet paper, and shave test. I will also try to cut a circle from free hanging paper.

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Johnathan Mitchell

 

[Jedi Knife]

See if it will "pop" a few hairs off of your arm, from both sides of the blade (provided it's not "chisel ground"). Then take a single sheet of newspaper and try to cut very thin strips off of it. A razor sharp, polished edge should do both of these easily.

JK

 

[Charlie Mike]

Get some Zig Zags or other cigarette papers and free hang it. If it cuts, then your knife is Scary Scalpel Sharp

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All you need in life is a good blade and enough smokes to get you through the day.
ICQ# 117419996

 

[rt014]

Sorry, but solid_soldier - What does 'free hang it' mean?

 

[Raptor]

<font face="Verdana, Arial" size="2">Originally posted by solid_soldier:
Get some Zig Zags or other cigarette papers and free hang it. If it cuts, then your knife is Scary Scalpel Sharp

</font>

ZigZags are for cigarettes??

I had it wrong all this time!!

--The Raptor--

 

[Dan Gray]

I take mine and hold it off my arm about 1/8" at the angle as if to shave the arm
If it catches the hair and cuts it off, I'm Happy
I have great respect for my knives.
They say a dull knife will cut you faster than a sharp one. This depends on what you call
Sharp.


...Dan...<A HREF="http://www.kynd.com/~graydg/kniveslist4.html">Gray Knives</A>


[This message has been edited by Graymaker (edited 06-26-2001).]

 

[Danbo]

First thing is to look at the edge. If you can actually see the edge, its not sharp enough. Then, I like to slide the edge across my thumbnail; when it grabs easily, it is sharp.

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Danbo, soul brother of Rambo

 

[corey smith]

must agree with Danbo. If, under close scrutiny, light reflects off the very top of the edge, then a couple more rough passes are necessary to cut the edge in.

 

[CUTIGER 3]

I use the thumbnail test, filet paper, and the arm hair "jumping off" test. My wife always rolls her eyes when I do the "free hanging toilet paper" test.

The guys I work with will not let me sharpen their knives anymore. They are scared I'll make them "TOOOOOO Sharp.... I just tell them there's no such thing

.

 

[HJK]

The classic test was trying to cut a falling silk scarf. Reputedly only wootz was able to do it. If you do manage to do it, your wife will probably use the blade the do a Bobbit. I hear the sharper the blade the less painful that is. That's what they said at choir practice, anyway.

 

[Jeff/1911]

These are geat tips...

Could someone please describe the "free hanging toilet paper test" for me?

Thanks, Jeff/1911.

[This message has been edited by Jeff/1911 (edited 06-27-2001).]

 

[Raptor]

Sure Jeff.

The "free hanging toilet paper test", at least how I have always done it anyway, is to be performed as follows.

First off, purchase yourself some non-cheapo TP like "Charmin" brand. *Note-This isn't a time to get cheap and cut coupons. Buy the good stuff for once. 'Ya hear me??

Now, reel off about 4 or 5 sheets.

Then, with your non-dominat hand, grasp only one sheet and allow the others to "free hang" below.

Then, snap your blade at the lowest TP sheet, minding your non-dominent forearm and non-dominent hand.

If your edge is really sharp it will just float on through the TP. If not, then the TP will be torn. Very few can achieve this level of sharpening perfection. Myself included most of the time. I have about 50/50 results so far.

Good Luck!!!!!!

--The Raptor--