Is there a special sharpening recipe for cleanly slicing napkins?

J

jalapeno

Joined
Jan 16, 2017
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I've noticed that knives that can cleanly slice slivers from a sheet of regular copy paper and that generally seem pretty sharp will fail miserably if you unfold a napkin to a single sheet, pierce the napkin and pull the knife down. It mostly just tears it.

Not that slicing napkins is an important use of my knives, but I was just wondering if there is something special about how to sharpen an edge (for example, maybe only highly polished edges work well?) so that it slices napkins (and other similar materials like paper towels) cleanly?
 
Thin... very thin with low angles... and refined toothy. That should get you there ;)
 
Well this is what I did for a quick try :
Super shallow angle sharpening bevel I don’t have a good way to measure it but it isn’t much steeper than the blade grind of this SAK Bantam. Probably six or seven degrees per side but that is a guess.

Does any one know that the main blade grind is on a similar SAK ?

The edge was already scary sharp but I took it to the 8000 grit Norton water stone (USA version; don’t count on the new Mexico Nortons to be as good I know they have problems)

Then onto the Shapton 15,000 (I used the other side of the stone but this one is more photogenic).

and you guys will be happy to hear I free handed it. And they said 'Bagger couldn't do that.

No stropping

I was carving curls off hairs that were still in my arm like crazy.

I didn’t want to cut up one of The Chef’s nice cocktail napkins so I went after one of her Puffs Plus Lotion facial tissues.

I wasn’t able to push cut once I pierced the tissue but moving slowly with just a slight slicing motion I was able to get a decent cut going.

My real test isn’t paper or tissue but my finger nail. If I can take off a bit of a curl rather than tiny chips then I have created a decent cutting edge. See second photo. After this one I was able to take a curl about 10mm long (yes I used a ruler) and that was push cutting. Try that some time; careful you don’t take off a bunch of skin while you are focusing on the nail.

Now I suppose if a guy wanted to bussssout a strop it could be a little better. I think at this stage it is edge geometry over a higher polish though.




 
Any reasonably thin edge <30° with a thin primary grind behind it should do this at almost any finish level. To unfold it and and shear cut it like a freehanging sheet of paper you'll be best off with something in the medium finish range, though again as long as its done well even a bright finish should pull it off.

This is one on my standard tests.
 
Agreed, it doesn't have to be so thin. A 15* edge finished on a 400 grit stone and stropped will slice a napkin. For a tissue finish finer. DM
 
I find it's more about the napkin than the knife.
 
I find it's more about the napkin than the knife.
Click to expand...

It's . . . ALWAYS . . . ALL . . . about the napkin.

(I don't know what that means but I just had to say it)
 
miso2,

My procedures with Edge Pro Apex.
Click to expand...

So what are you saying ? The Edge Pro produces a "better" edge ? ? ?
That my hand sharpened edge is some how "inferior" . . . ? . . . ? . . . ____
:grumpy:
:mad:
:(
:o

Oh . . . wait . . . that's what I always say too.

So much for 15,000 grit and all like that.
I'll give 'er a go with my 4,000 Edge Pro and see if I can get it up to your performance.
Good one !
 
miso2,

What the heck . . . you have clearly ANNIHILATED the napkin.

Any chance of the same demo with a Kleenex ?
I just want to see how far I need to go to get to sharp.
 
Nothing like hogging the thread to death.

Hey guys I was noticing last night that my 15,000 Shapton Pro is pretty loaded up in the pores though the surface isn't all that black just lines here and there.
Can you provide a link to what to do about that.
I reread the info, just to be sure, not to use cleanser or soap on it.
Normally I would just lap it on my 330 or what ever grit DMT plate with the little round dots (holes) all over it. I am adverse to getting the Shapton lapping stuff just for this.

Generally I use a natural nagura stone on the sharpening stones 8000 and bellow but not so much on this 15,000


The instructions say to just keep it wet while I am using it. I admit to using it a bit dry for edge trailing so I can see when the edge is just getting down to the stone.

What is the best way to keep the fine grit characteristics but clean the pores ?
 
Wowbagger said:
miso2,

What the heck . . . you have clearly ANNIHILATED the napkin.

Any chance of the same demo with a Kleenex ?
I just want to see how far I need to go to get to sharp.
Click to expand...


Yes. I have finally succeeded in conquering it. I will see if my edge can match Kleenex......

Miso
 
Daniel,

Why cut napkins?
Click to expand...

. . . because
They Are There.

The Chef said just what you said; why cut napkins.
I said how do you test a knife then to see if it is sharp enough.
She said if my tomato knife cuts a tomato it is sharp enough.

I said what if it is a pocket knife ?
The Chef says : If it cuts your pocket then it is sharp enough.

I don't know . . . I'm just the messenger.
 
Daniel said:
Why cut napkins?
Click to expand...
Hi,
its a "tricK" a way to demonstrate a some level of sharpness, like head hair whittling is to show a high level of sharpness

Its also tricky because lots of little changes can affect if its possible to perform

For example in miso2's video,
it shows very high sharpness,
but how to compare it?

- paper looks thin and very bendy , not thicker like charmin (+difficulty)
- looks and sounds more like cocktail napkin or paper towel than toilet paper (-difficulty)
- cutting going cross grain (+difficulty)
- seems to pull the paper is kind of tight (-difficulty)
- cutting at an angle (45?) due to shape of blade (-difficulty)
- speed is not super slow ( -difficulty )
- speed is not super fast ( +difficulty )
- edges of the cut paper are very smooth (+difficulty)

so his is a very sharp blade
with edge polished to a very high grit
but change the way you cut and you can do it with much much coarser grits
 
My opinion: It is a waste of time. If you want a blade that is good for slicing napkins, tissue, or toilet paper, then I guess that it makes sense.

Unfortunately, that type of edge is not going to last very long and is of limited value for any other task.
 
Just for clarification. My edge is not highly polished.

I stop at #600 stone, of which grit size is supposed to be 10 micron according to the Grand Unified Grit Chart, and lightly deburr with a #1,000 ceramic rod, which should be around 5 micron. The stropping compound I use is rated as 3 micron grit (#4,000 Shapton equivalent).

So the edge stays toothy to some extent and is refined enough to cut soft materials clean. I just like this kind of edges even though coarser edges may serve me better.

Obviously, this test is not really necessary either. I just use it to test whether the edge is refined enough without remaining burrs or edge inconsistency. I found it useful when sharpening steels with high vanadium contents, which are difficult to refine (for me), and learned that I need diamond abrasives for those steels through this test.



Miso
 
miso2 said:
Just for clarification. My edge is not highly polished.
Click to expand...
Hi,
What do you mean , are these not very high grits?
You setting the edge with 10 micron or P2000 grit common automotive sandpaper grit rating used for high polish, after which they use buffing compound for a mirror polish
Then deburr with 5 micron or P5000 grit
Then strop with 3 micron compound ... thats more than P6000 grit

That progression is in the comfortable face shave region ,

Yes the edge bevel might not have a 3 micron finish (might need more passes for that),
but the apex surely is very close if not 3 micron or higher finish
as the apex is very very small 1micron or less
 
I guess "high" is a relative term. What I meant was that I don't use very fine abrasives in the micron-submicron range for a high or mirror polish. If you define the edge after P2,000 highly polished, it is highly polished.

As you pointed out, I also do not think the edge finish is actually at 3 micron, as I can see remaining P2,000 scratches near the apex under microscope. And you are right that the apex should be refined to 3 micron or less. So my fantasy is that the edge is like a very fine (10 micron teeth) and keen saw. I actually want to stop at a #400 stone (20 micron) or #320 (30 micron) to make it more toothy. But burr removal is a bit difficult from there in my hand……


Miso
 
You need a keen but aggressive toothy edge cleanly debured. Low edge angle preferably < 20dps at apex. the edge should pass the 3 finger test and grab your thumbnail both across AND ALONG the the edge. It should slice paper towels, toilet paper and tissue paper

The way I accomplish this keen but highly aggressive edge is to use fine grit silicon carbide abrasive paper. 1200-2000 grit. Instead of using a mouse pad I use a rod of any hard material. Steel rod or wd40 can or a thick marker pen. wrap the abrasive paper around it tightly then use sharpening strokes on it as you would on a sharpmaker rod. The 1200 grit will be a little coarse at first but break down nicely after use and offer more refinement. You can use both edge leading and stropping motion to quickly establish the apex. I finish with alternating very light edge leading strokes. The sharp silicon carbide abrasive create a notably more biting edge than off stones. It should bit hard on soft napkin material yet should be refined enough to sail through thin magazine paper with a whisper quiet hiss.

I might add that such edges aren't entirely useless or just for show. In rare cases it may offer some advantage to the usual highly stropped edge. I like this edge for slicing steak and meats. It cuts them nice and clean with little effort. But beware this edge is highly dangerous to skin!
 
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