Thread: Explaining the thumb test

Kees, TNT is not a sharpness test, and it should never be your first test, because it will dull a sharp edge.

Do your sharpness test when you first pick up a razor, whatever it is (HHT?). If your showing some grab, you shouldn't do the TNT, but just tone up the razor on an 8K (or do a conservative pyramid with a test in the middle). Even a razor that has just passed the TNT will show a decent amount of sharpness (grab on the thumb test).

I would only do the TNT on a razor after it shows a poor result in your sharpness test, whether the razor is previously sharp or new (Ebay). It may not need a lot of work.

Basically, you need the TNT to tell you why a razor is not sharp, if you can't seeit by inspection. If it passes the TNT, you know you're not far off, but you do need to hone it to keenness. You would not want to use a lot of 4K then.

If it doesn't pass, you'll know if the razor is dull, has a wire edge or an invisible chip (and where it is). These are all defects that require you to restore the edge (starting with the 4K), and the TNT tells you how to proceed (do you need to back hone or work out a chip on the 4K alone?, with circular strikes? or do you just need a pyramid- should it be aggressive or not?).

The idea is you know what each razor needs, and you're not jumping in blindly and doing a bunch of pyramids that put a close edge out of reach. A chip takes a lot longer to remove with pyramids than with circular strokes on the 4K. A wire edge will be fixed quicker with back honing than with a bunch of pyramids. You need to do what's right, not jump in blindly.

I'm not suggesting that any of this applies to you. I'm just explaining why , how and when to use the TNT. It and an inexpensive microscope will keep you on track.

Guys, I'll be the first to admit that the information out there about the thumb test is not the most complete, and I understand where the questions are coming from.

I also would be confused about how to move the thumb from the information I found.

But I used to go to an old school Italian barber a long time ago (since I was a youngster), and I used to see him do it all the time. This was in the days when the traditional shave was all that barbers knew, and this guy was a master, so well respected that he was doing shaves most of the time (usually not on business days, but certainly all day Saturday).

I guess the feel of the razor on a customer's face tipped him off, because he would often strop without any test. But occasionally I'd see a thumb test, followed by stropping. He also did it when he switched to another razor. He carried a barber hone in his pocket but rarely used it during a shave. Between shaves, he would sometimes do a few quick swipes on the hone on a razor he had put aside. From talking to him I know he didn't do any real honing. He used a service.

Not to change the subject, but Joe L. indicated that a sharpness test should be done first. What are some good sharpness tests other than the HHT? My wife's hair is very fine and doesn't seem to work well for testing. Mine's to short and I don't have a dog. Any ideas? Thanks.

Jordan

I know that one SRP memeber (don't remember who) uses a cheap or old shaving brush, you could also go to your local hairdresser's and ask for clippings.

I'm not Joe or Lynn or anybody talented, but I don't do the HHT, it doesn't work for my hair at all. I use the thumbnail test very infrequently (just on newly-received ebay blades) to check for nicks, and primarily use the thumb pad test in the final stages of honing, or if it's getting a touchup on the barber's hone. Mostly I just check to see how well it cuts my arm hair, as it gets sharper on the 4k it will start cutting hair on the top of my arm above the skin, and as it gets sharper on the 8k it will start cutting hair on the bottom of my arm above the skin (I get better results if the hair cuts and falls on the blade than if the hair pops off the edge). Once it's spent some time on the 1 micron paddle or the 15k shapton, though, the blade stops passing either of these tests on my arm so I have to use the thumb pad test. The ultimate test at that point is to try and shave with it, and see how it goes. I'm generally really close at that point though so if it isn't quite right it's only a few more laps on the shapton or the pasted paddle to dial it in.

Everybody does things a little differently though, which is one of the reasons honing is a bit tricky to learn. The key for me was figuring out exactly which tests worked for me, and figuring out the type of edge I like on my razors and how to use the tests and hones to get there.

One thing that really helped was getting a razor sharpened by a honemeister (in my case Joe Chandler) and using it to evaluate and calibrate the various tests so that I could better evaluate my own edges as I was honing. I started out on shave-ready razors so I knew where I wanted to go, but once I had the honing basics down and was trying to improve my technique I really needed a fresh honemeister edge as a comparison -- I've only shaved with Chandler's blade once or twice, but it's been poked and prodded six ways to Sunday while I was working on my own technique. Thanks, Joe :-)

(I've heard that badger hair works fine for the HHT, never done it myself but if that dovo doesn't stop losing hairs it may be sacrificed for the cause...)

I use the thumb test. I have never been able to get the HHT to work for me with any razor honed by anyone, even the best.

You're supposed to use hairs as close as possible to the ones you're actually cutting. Otherwise I wonder how reliable it will be.

There's a visual test that someone mention here where you look head on at the edge in a strong light and see if you can get the edge to reflect light at any spot (that's a sign of dullness). This is an old knife sharpening test. The problem I have with it is that a razor needs to go past that point. You will pass that test before the razor is keen. In fact, you'll probably pass it when the razor comes off the 4K.

The ultimate test is the shave. The only reason you need these other tests is that you don't want to have to jump back and forth constantly between honing and shaving. So, a useful sharpness test is something that has a high probability of telling you when you'll pass the shaving test.

Joe,

Maybe we are talking about the same thing, and maybe not, but...

I have been using the thumb test for over 20 years, and when I run the ball of my thumb lightly along, parallel to, not across perpendicular to, a keen edge immediately after stropping, it does "stick" or "draw" and that is exactly the sensation you should be looking for. Yes, it would slice my thumb were I to use more pressure and/or draw my thumb along the edge in a single movement, but this is the way it's done.

Check any standard textbook on barbering to confirm that this is the correct way to do the thumb test.

Scott

Originally Posted by honedright

Joe,

Maybe we are talking about the same thing, and maybe not, but...

I have been using the thumb test for over 20 years, and when I run the ball of my thumb lightly along, parallel to, not across perpendicular to, a keen edge immediately after stropping, it does "stick" and that is exactly the sensation you should be looking for. Yes, it would slice my thumb were I to use more pressure and/or draw my thumb along the edge in a single movement.

Scott

And I'm saying it shouldn't along the length of a keen edge. In it's cutting direction, a blade will stall a lot if it has chips or a wire edge. A keen edge, however, should feel perfectly smooth, as smooth as the bevel. The termination of the striations forms the microserrations. I've never done it and I never will, so I can't tell you from experience, but I'm wondering what could grab grazing skin along a keen edge that wouldn't grab a whisker rather than cut it. When I move my thumb lightly along the bevel it feels smooth.

Where did you find your test? Is it described anywere?

Joe,

To do the thumb test correctly, you do run the thumb pad along the cutting edge, not the side of the edge, or bevel.

Any defects in the edge will be detected and corrected by doing the thumb nail test while honing, so nicks, wire edge, etc, shouldn't be a factor in doing the thumb test after stropping.

I'm not advocating that anyone do this if they feel uncomfortable with it, but this is the way it's done.

My source was and is, "Standard Textbook of Barbering", Associated Master Barbers and Beauticians of America, 1950, p. 25 (the thumb test was also demonstrated to me by a barber once, along with honing and stropping).

Scott

Outside of razors, I've sharpened knives for a whole bunch of years, starting when I was just a wee sapling. No telling how many of my dad's knives I ruined trying to learn. As I got older, I got more into the "theory" of blade sharpening, to learn why certain things with knives, stones, and other abrasives do what they do. Why, for example, an Arkansas stone cuts they way it does...why certain stones produce better edges faster, etc. The one thing I've learned is that if you take 50 knives, with 50 different people, all of whom were taught to sharpen by the same guy, you'll still get 50 different results and 50 different techniques. Same with the tests. Everyone adapts what they learn to their own style of doing things. Hence, in this example, there's about 50 different ways to skin the same cat. All the tests are in my arsenal, but the arm (now leg, since my right arm is bald ) hair test and shave are the most consistent for me. I'll use the others when a blade acts "funny" and doesn't give me the expected results, to focus my efforts and point me in the direction I oughta be going. Every test imaginable should be learned, because some day, that test will be the only thing than answers the question a particular blade asks. You might use it seldom or never, but it's there if you need it. The point is, use the "common" understanding of a test as a basis, marry it with experience, and you'll figure out how to make that test work for you to achieve the results you want.