How do you like to test for sharpness?

I use the fingerprint side of my thumb to start with but it isn't real accurate.

My final test is to cut the thin shiny advertisement pages in the Sunday newspaper. Unfortunately sometimes they use different types of paper.
 
I think cutting phone book paper is an excellent gauge for sharpness. You can easily determine if the full length of your edge is clean and consistently sharp. It tells you more than shaving hair does.
 
I guess I have a fixation or am not very creative.
I thought of the other test I do. I test the edge by carving chips off my finger nails. When it is sharp AND THE GEOMETRY IS RIGHT it takes a controlled chip . . . when I have the edge geometry the way I like it I can take a longish curl like off my thumb nail here



and when I got 'er cranked down and dialed into "Oh My Bob That is AWESOME !" this is what happens with out too much effort.



When I don't quite "have it" all I get is minuscule little chips that pop off before I want them to.

Careful ! When it is cutting curls it will take off skin off of your finger tip and you won't feel it.
 
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I feel the edge (Carter 3-finger test), cut newsprint and move the blade near my arm to see if it catches the hairs (no shaving). For chefs knives I sometimes check on tomatoes.
 
When I need to shave my facial hair, I will grab several knives and test them out for sharpness. It usually only takes one pass with the blade... but if I find that I need to take multiple passes, I will touch up the blade with a ceramic rod. I like to rotate my EDC sets, so I tend to keep them in good shape most of the time because I will clean and touch up on the blade before bed (for the knives that I EDC'd that day/s). But yeah... I really don't have a specific method of testing out the sharpness. I use most of the methods provided by previous commentors (depending on where I am and what's near me etc.).
 
i run accost my finger/thumb,not recommend for the new at sharpening!also use phone book paper for testing how the blade slices tough.
 
S cut and push cut whatever free paper is around, although most of the time S cuts are good enough and I really need to be motivated to get to push cuts, e.g. a new steel, geometry, correcting problem bevels -
 
I've been looking for the answer myself, so many people have their own method and definition of determining whats "sharp".

So i take what others claim to be a good way to tell if it's sharp, and i do it. They say you can't please em all, well, you can certainly try.

Here's my album on FB logging all the "tests" and work i've done. Some, especially older works, weren't as properly done as i would done it now.

https://www.facebook.com/media/set/?set=a.10155139063049140.1073741833.678064139&type=1&l=4ab4e24e82

Rolled up newsprint, vertical and horizontal standing paper, cutting a stack of newsprint, slicing paper towels, splitting hair, pushing a piece of newsprint into the edge, slow slice newsprint to check for chips or carbide tearout, light above the edge to check for flat spots, etc. The list goes on
 
Newspaper is IMO a harder test than phone book paper even though its a little thicker. Its quite limp and the grain is more directional. When cut across the grain it is easily teared if knife isn't very sharp. I like to test for edge refinement by cutting a sheet of newspaper straight down 90 deg across the grain and from end to end without tearing. If it does that then it is very sharp. If it can do it by pure push cutting then it is extremely sharp but that often require a more refined polish which may not be the best edge for stuff like tomatoes.
To test for bite I like to use my thumbnail but not in the conventional way. I put the edge on the thumbnail then try to gently do a slicing action as opposed to a sideways motion. If the edge bites in and grip hard on my nail then it passed and the edge great bite. If it slides a little but I feel some friction then it still has good bite. If it slides a little more easily then I use nail on the tip of my forefinger. Here if I feel some friction then it still has some bite. If the forefinger nail failed then I consider the slicing bite to be quite inadequate for task such as meat and thick skin vegetables. At 1k - 6k grit the edge it should not slide easily across thumb nail. If it slides then it probably not fully apexed or overly polished or rounded over by stropping. But this test isn't very applicable for very coarse grit edges or high polish edges. I also do the 3 finger test. But now I find the thumbnail test much safer.
 
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