Best way to tell if a razor is sharp enough without actually shaving?

[Dundee]

I am wondering if people here have a good test to indicate a razor is sharp enough to shave with, without actually shaving with it. I tend to do kind of a trial and error approach, where I just hone and shave, but I also try to make sure it can at least pass a hanging hair test. I also keep a goatee and will see if it tree tops the goatee hairs.

Curious if there's any other handy and accurate ways.

 

[silverlifter]

Treetopping arm hair at 10mm tells me it should be good to go. Doing so with a plink sound is more encouraging. Doing so absolutely silently and without disturbing the hair under the blade is a cause for a beer...

 

[Legion]

I find the way it performs the hht is a pretty good indicator. You should try to standardise the hair as much as possible.

 

[Steve56]

Yep, HHT/treetopping. A10x loupe is also helpful. If you have a straight, even edge with no shiny lineys, sparkles, low areas, etc, that’s a pretty good indication that the edge is well done.

 

[Gamma]

Honing feedback.

 

[lightfoot]

This is a tricky question because you can have one of those razors in which the bevel was 97% set but not fully set and still have encouraging HHT results.

Such a Razor may pass HHT but can have a sensation during the shave that might lead one to believe that you only need to go back one stone in the progression when in fact the bevel isn’t really 100% ‘there’.

So when it comes to pass/fail checks in my personal honing efforts the only thing I really try to get laser-focused on is whether or not the bevel is fully set.

Now if we assume that the bevel is in fact fully set I have found that if I can pass the blade a good height above the arm hair and it silently cuts through without pulling at the root I might be inclined to go ahead and shave with it but even this test is highly misleading unfortunately.

So again I aim the really intense scrutiny at the very first stage of Honing more so than any other point.

 

[JPO]

I am wondering if people here have a good test to indicate a razor is sharp enough to shave with, without actually shaving with it

99% of the sharpness (min edge width at 3 micron behind the apex) is reached quite early in the progression, maybe at around 5-6k. After this you are primarily improving the smoothness of the edge. I feel my edge with my thumb pad during bevel set. At 5-6k i see how well it cuts arm hair. After this the feedback on the stone, and the water displacement tells me the rest.
A 10 to 15x loupe is also used along the way.
If you get to focused on passing different test, you actually loose focus of what is important. The razor might still pass different tests even if the undercut is not were it should be.
Be careful about false positives. If you did something wrong during the mid range work, the razor might still pick up some resistance when you finish. This might just indicate the the bevel face is polished and matching the surface of the stone.
You still need to read the other tells.

 

[cugel]

Despite all of its shortcomings I like to use the hht. The biggest reason being I can surmise how different parts of the blade are behaving.

 

[Wid]

I do go by feedback of the stone and the way it under cuts on the edge but also use magnification to help judge the edge.

Bevel, bevel, bevel. That’s where one should concentrate most of their work as without it being spot on the rest doesn’t matter.

In the very end I use HHT as a final test. Once you have a calibration HHT you can tell how the edge will perform.

Just as important is to learn either the thumbnail test, tomato test or test shaving arm hair for the bevel.

 

[SliceOfLife]

Root in, > 3/4" from grip silent fall HHT with my head hair is pretty definitely a good shave...

but everyone's hair is different so you've got to figure out the metrics for yours to get much of a reliable result.

And only immaculate edges really HHT well enough to be a sure thing for me. Same test that's a little grabby instead of silent fall, could be a decent shave, could be bad.

 

[Jakebullet]

I’m not at the stage where I can tell the difference between good and half good edges from the feedback of the stone.
I use the HHT but it’s so subjective.
I can’t use my own hair as it’s too short, so I either grab a hairbrush or find a hair lying around.
But I have a girlfriend and three daughters, one is a baby but the others, 3 and 7 all have long curly hair.
The three year olds hair is very fine and twists and curls this way and that, her older sisters are the same.
The girls mam has quite straight hair, generally thicker and easier to cut than the little ones but whose hair I’m cutting is usually a mystery to me.

 

[Mr Kooby Shemayrew]

If I do a HHT and the hair is cut perfectly and silently then I know… someone has been in my house using my hones and razors.

 

[H Brad Boonshaft]

The “Best” way is to perfect/calibrate your test, whatever that is.

The easiest quickest way for me is a visual test, look straight down on the edge, if you see any shiny reflections on the edge, the bevels are not fully set, and microchips will cut you or at the least feel harsh.

No doubt there are folks that have perfected/calibrated hair test, TPT or others, and that works for them.

And that is the problem with most tests. What exactly does a fully set TPT test feel like? If you hit a razor with a handheld hair and it does not cut, but cuts on the second attempt, is that a pass or fail?

A visual test is pass or fail, no grey area, and dirt simple to teach so someone.

Look at the 2 photos below. First photo, an Almost set bevel. Second Photo a fully set bevel.

You just calibrated a visual test, congratulations.

Almost set Bevel.

Fully set Bevel.