blade edge

[hotreds]

Is there a way to tell if you have a good edge on the blade? Will a loupe help? I just want to be sure that it is my lack of technique rather than a dull blade that is causing the "ouches" I feel when shaving.

 

[Mike H]

From the wiki...

Sharpness Tests

There are four standard tests for evaluating the keenness of a straight razor: TNT (Thumb Nail Test), TPT (Thumb Pad Test), HHT (Hanging Hair Test), and Shave test. Some of these tests are controversial, and it is important for each honer to develop an individual feel for analyzing the feedback provided by these tests. Dismissed by some as "parlor tricks", sharpness tests can be useful in helping the honer evaluate where the edge is in the journey to shave readiness.

TNT

The TNT is done by wetting the thumbnail and dragging the edge of the straight razor along without applying any pressure (blade weight only).

Interpretation

The TNT is very useful in determining where you are in the bevel setting process. A razor that has a properly set bevel will begin to cut into the thumbnail smoothly without a gritty sensation. If the blade slides over the thumbnail without cutting into the nail, the razor is not keen and additional work needs to be done on the stones. If the blade does cut into the thumbnail, but with a gritty sensation, the razor could be over-honed and corrective steps may need to be taken. Correcting over-honed razors is a topic beyond the scope of this article and should be discussed in the http://badgerandblade.com/vb/forumdi...=80honingforum.

Drawbacks

While the TNT can be very helpful for determining if a bevel is set, it can provide false positives and is not really useful for determining the shave readiness of an edge. With a razor that has been maintained on pastes, a convex edge can develop. In order to restore the edge to a proper bevel, all of the convexity should be removed. One way to avoid this false positive is to very gently do a single bread-knife stroke on the bottom of glass rendering the edge unable to shave arm hair.

Another drawback of the TNT is that it can damage the edge of a shave ready razor. For this reason, it is generally not considered good to perform this test after the initial bevel setting process has been successfully completed.

TPT

The Thumb Pad Test (TPT) is another sharpness test that utilizes the thumb pad to determine the keenness of the razor's edge. There are two schools of thought on how this is done. Whichever method is used, in order to increase the sensitivity of the honer's hand, it is helpful to hold the razor in your dominate hand with the edge facing up. Then, the non-dominate hand is used for testing with the fingers under the spine to enhance the sensitivity of the thumb. The TPT is conducted with a moist thumb pad.

Plucking the Edge

Some people people do the TPT by drawing their thumb across the edge (not along it) while feeling for indicators. The properly honed edge will give a slight tickling sensation when the thumb is gingerly dragged across. If there is a biting or catching sensation, there is a possibility that the razor has been over honed. When performing this test, the ideal edge will perform much differently than a sharp knife with a good cutting edge. If the sensation is similar to that of a sharp knife, the razor is not ready for a shave test.

Barber Manual Version

The TPT test as taught by Barbers Manuals differs in that the thumb pad is dragged along the edge of the razor (not across it). The properly honed edge will produce a slight sticking sensation. That is the razor cutting into the thumb of the tester. It is important not to use too much pressure because that will result in cutting into the thumb and drawing blood.

The TPT should be performed all along the edge until all of the edge performs equally.

HHT

The Hanging Hair Test (HHT) is possibly the most controversial of all the sharpness tests. This is due to many factors, but because of this controversy, it has been dismissed by many as a "parlor trick". Many shavers have razors that can not pass the HHT that shave great, while others have razors that pass the HHT that do not shave well. Some honers believe that a truly keen edge will pass the HHT by silently causing the hair to fall upon coming in contact with the razor's edge. Others believe that the closer to perfection the edge gets, the more difficult the HHT is to pass. For determining the merits of these arguments, visit the honing forum.

For the HHT to be meaningful, it should be standardized as much as possible. http://coticule.be/hanging-hair-test.html This article on the hanging hair test may prove useful for informing and evaluating your honing tests by offering a standardized test and a means to interpret the results of that test.

 

[DominoM]

I just got a 40x 25mm loupe so I could see the edge on my razors better. I was using a 20x 12mm one and even that was enough to help see what was going on at the edge, but it was a little small and fiddly to use. So I "upgraded" to an ebay cheap one with built in LED light. Well worth the £3.50 (~ $5) it cost - you can definately see how good (or bad) the edge is with it.

 

[hotreds]

Thanks, gentlemen!

 

[Kentos]

Most if not all the tests are a relational one, where you are comparing the razor you are testing to one known to be sharp.

I would pick up another shave ready straight, or rehone the one you have now, and perform your tests on that one as your base line.

The HHT and TPT are likely the best, IMO, as performing those tests won't have as much potential to degrade the edge.