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Razor Blade Sharpness Testing

If you are only interested in the Razor Blade Sharpness Summary and already know how the testing works, click here to see summary tables.

I have a background in Materials Engineering, so naturally as I continued to try different blades I started to look for a way to compare the properties based on measured data. As I searched the internet I realized I was not the only one interested in this information.

The 3 main areas of razor blade performance (in my opinion) are:

  • Smoothness / Feel
  • Sharpness
  • Durability (Edge Sharpness Retention)

Smoothness and feel will be subjective and different for each shaver. Because of this, there are really only 2 ways to rate smoothness: I will give my review for each blade and each blade review post will have an area for users to leave their rating. Please take the time to go to the razor blades that you’ve tried and rate the blades. The more people that respond the more useful the data will be to others.

As I looked into sharpness testing, I realized at school we had all types of destructive and nondestructive testing in our labs for strength, hardness, toughness… the list goes on, but there was nothing for “sharpness”.

I did find one company overseas that has a machine to test edge sharpness.  After contacting this company I found the cost per blade to be cost prohibitive based on the quantity of blades and the types of tests I wanted to perform, and not practical considering blades need to be tested after each shave.

I was able to find another company in the USA that sells a piece of equipment that would work perfectly for this purpose.

Expand The Panels Below for More Information

How it Works:

A digital scale is purposed to hold a clip with a pre-tensioned piece of test media. The blade edge (in this case a razor blade) is then pushed against the test media until it is severed. The scale is programmed to record the maximum force required to cut the test media.

The logic is that the lower the force required, the sharper the blade. The grams required to sever the test media is then considered to be the sharpness value.

To be consistent, a jig has been fabricated to hold the razor blade. Brass strips are used to make sure there is no bend in the blade, and the blade itself is affixed to sliding rails to make sure all the blades sever the test media clip at exactly the same angle.

Click to see the Tests:

Razor Blade Sharpness

Due to the sensitivity of such fine values and some very slight variations in the blade edge, a truncated mean (average) will be used. You can see in the picture below that the razor blade edge is not perfectly consistent all the way across.

4 readings are taken from each side of each blade, and the highest and lowest overall reading will be discarded. The average of the remaining 6 readings will be the given sharpness value for the blade. The logic to this type of statistical average is that if there is one significant outlier reading, it will not significantly impact the overall average.

A table of values will be published by brand so that shavers can get an idea of how sharp each brand of blade is compared to each other. 

Please note:  Just because a blade is sharper, does not mean it is better.  This is just to give an idea of how the blades initial sharpness compare to one another.

Razor Blade Durability (Edge Sharpness Retention)

This test is designed to see how long a blade will last, and the consistency of the shaves.

Each blade will get its initial sharpness value based off 6 readings. I will then shave once, and then take 6 more readings (I will be as prudent as I can to ensure I am using both sides equally). I will then shave one more time, and then take 6 more readings after the second shave. 

This will give a factor for how long each blade can retain its initial sharpness, and might provide some insight as to how many times you can use a blade.

The factor will be (current reading/previous reading), so a factor closest to 1.0 will be the most consistent. A factor of 1.0 will mean the blade did not lose any sharpness, a reading of 2.0 will mean that it took twice as much force to sever the test media, so the blade is essentially half as sharp as it was. A factor of 0.9 means that the blade edge is about 10% sharper than it was.

Again, note that this will have no bearing on the blade coating or smoothness, so the blade may loose smoothness while still retaining edge sharpness.

Of course, YMMV (your mileage may vary). Please note that I shave my head and my face, so each one of my shaves may be equivalent to two of someone that is just shaving their face. I also have relatively strong growth, except for the top of my head. To be consistent, all shaves will be done using 48 hours of growth (+/- a couple hours) using a Merkur 34C.

After the second shave I usually toss my blade regardless, which would equal about 4-5 face only shaves (I shave my head and face). Once the baseline testing is completed for all the blades (initial sharpness and after 1 and 2 shaves) I plan to return to some of the blades and see just how many shaves they can be pushed.

Click to See Video Demonstration

Here is a video demonstration of a test on a Feather Razor Blade. If you listen carefully you can hear when the test media is severed.

Click to See Data Summary – Sharpness

Check out the full Razor Blade Reviews for the razor blades showing data. It takes time to test the razor blades, a new blade will be released each week. To be notified of new data, sign up to receive updates.

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The blades listed with no data are currently in my shave den awaiting testing in no particular order. If there is a specific blade listed and you are eager to see the results, vote further down this page to see it next.

DescriptionSharpness
New Blade
Sharpness
After Shave 1
Sharpness
After Shave 2
Sharpness
Average
Astra
Superior Platinum
49464446
Astra
Super Stainless
43384040
BIC
Chrome Platinum
40333235
Bolzano Superinox Inossidabile52464949
Crystal44373840
Derby Extra
(Green)
53445149
Derby Premium51464648
Feather32404037
Gillette 7 O'clock
Permasharp Stainless
(Green)
45354241
Gillette 7 O'clock
SharpEdge
(Yellow)
46434244
Gillette 7 O'clock
Super Platinum
(Black)
45323638
Gillette 7 O'clock
Super Stainless
(Green)
45384041
Gillette
Nacet Stainless
39353837
Gillette
Platinum
45383941
Gillette
Rubie Plus
50454145
Gillette
Silver Blue
46413541
Kai
Stainless Steel
53423945
Merkur53514650
Perma-Sharp
Super
41303736
Personna
Comfort Coated
(Lab Blue)
48373540
Personna
Platinum
(Israeli Reds)
41373638
PolSilver
Super Iridium
46394042
Rapira
Platinum Lux
44383940
Rockwell Razors54515453
Shark
Super Stainless
47515651
Treet
Carbon
(Black Beauty)
52626961
Voskhod42413941
Wilkinson Sword
(German)
46333438
Wilkinson Sword
(Gillette)
43404141
7 am
Hi-Platinum
Dorco
ST-300 Platinum
Dorco
ST-301 Stainless
Ladas
Super Stainless
Lord
Super Stainless
Rapira
Stainless Chrome
Rapira
Super Stainless
Rapira
Swedish Super Steel
Schick
Premium
Shark
Super Chrome
Treet
7 Day Platinum
Treet
Classic
Treet
Dura Sharp
Treet
King Super Stainless
Treet
Platinum
Click to See Data Summary – Durability

Durability factor is calculated as (current reading/previous reading). A factor of 1.0 will mean the blade did not lose any sharpness, a reading of 2.0 will mean that it took twice as much force to sever the test media, so the blade is essentially half as sharp as it was. A factor of 0.9 means that the blade edge is about 10% sharper than it was.

DescriptionDurability
/Edge Retention
After Shave 1
Durability
/Edge Retention
From Shave 1-2
Durability
/Edge Retention
From New to 2
Astra
Superior Platinum
0.940.960.90
Astra
Super Stainless
0.881.050.93
BIC
Chrome Platinum
0.830.970.80
Bolzano Superinox Inossidabile0.881.070.94
Crystal0.841.030.86
Derby Extra
(Green)
0.831.160.96
Derby Premium0.901.000.90
Feather1.251.001.25
Gillette 7 O'clock
Permasharp Stainless
(Green)
0.781.200.93
Gillette 7 O'clock
SharpEdge
(Yellow)
0.930.980.91
Gillette 7 O'clock
Super Platinum
(Black)
0.711.130.80
Gillette 7 O'clock
Super Stainless
(Green)
0.841.050.89
Gillette
Nacet Stainless
0.901.090.97
Gillette
Platinum
0.841.030.87
Gillette
Rubie Plus
0.900.910.82
Gillette
Silver Blue
0.890.850.76
Kai
Stainless Steel
0.790.930.74
Merkur0.960.900.87
Perma-Sharp
Super
0.731.230.90
Personna
Comfort Coated
(Lab Blue)
0.770.950.73
Personna
Platinum
(Israeli Reds)
0.900.970.88
PolSilver
Super Iridium
0.851.030.91
Rapira
Platinum Lux
0.861.030.89
Rockwell Razors0.941.061.0
Shark
Super Stainless
1.091.101.19
Treet
Carbon
(Black Beauty)
1.191.111.33
Voskhod0.980.950.93
Wilkinson Sword
(German)
0.721.030.72
Wilkinson Sword
(Gillette)
0.931.030.95
7 am
Hi-Platinum
Dorco
ST-300 Platinum
Dorco
ST-301 Stainless
Ladas
Super Stainless
Lord
Super Stainless
Rapira
Stainless Chrome
Rapira
Super Stainless
Rapira
Swedish Super Steel
Schick
Premium
Shark
Super Chrome
Treet
7 Day Platinum
Treet
Classic
Treet
Dura Sharp
Treet
King Super Stainless
Treet
Platinum
Click to See Raw Data

Legend:

New = Fresh Blade
S1 = After Shave 1
S2 = After Shave 2

Tx = Reading Top of Blade
Bx = Reading Bottom of Blade

DescriptionNew
T1
New
T2
New
T3
New
T4
New
B1
New
B2
New
B3
New
B4
New
Avg.
S1
T1
S1
T2
S1
T3
S1
T4
S1
B1
S1
B2
S1
B3
S1
B4
S1
Avg.
S2
T1
S2
T2
S2
T3
S2
T4
S2
B1
S2
B2
S2
B3
S2
B4
S2
Avg.
Astra
Superior Platinum
544849464947534849455339404841525246364246434546404944
Astra
Super Stainless
354945425142413643384032354140383738434742413635364140
BIC
Chrome Platinum
424440384141383440333342363432312933372733372636282832
Bolzano Superinox Inossidabile505354464351555652504150464940414846534949405049485049
Crystal414742454644374944344038333639403237413437374141393438
Derby Extra
(Green)
576159574556414653505150563835373444505759553946534251
Derby Premium424652516156603351495042463743454846464440516043464546
Feather33392829313132364142563943333740385036433542394240
Gillette 7 O'clock
Permasharp Stainless
(Green)
484362513341414645493338583130282635504236524440344142
Gillette 7 O'clock
SharpEdge
(Yellow)
424546394742525146414741504338424343424136464642433442
Gillette 7 O'clock
Super Platinum
(Black)
484244424249474745313127373335243932393734392939313736
Gillette 7 O'clock
Super Stainless
(Green)
444541454852444445393934373736374038414742383440413840
Gillette
Nacet Stainless
384243373944263539383633402832363735334136343447354738
Gillette
Platinum
474650463746414145404244433333343338433541373436404439
Gillette
Rubie Plus
635046724831464450724643544337433845544034594134383741
Gillette
Silver Blue
454552534348403446414332354543423741283131373745363635
Kai
Stainless Steel
545448575654525053373832434246494642374335344049433739
Merkur494852586150565553525151505054515051475044514248474046
Perma-Sharp
Super
423938364441444041343329272731282930403631293455325037
Personna
Comfort Coated
(Lab Blue)
525552474140504648453634383539273837293935333437364235
Personna
Platinum
(Israeli Reds)
424648374338373941323238394232413837363634383736353436
PolSilver
Super Iridium
384338485055475246373636364747324239444436544236373440
Rapira
Platinum Lux
454248425047424144383438364037414238454141403739353839
Shark
Super Stainless
464836455456434747494757544255525051485648645357606656
Treet
Carbon
(Black Beauty)
594453426148575152716058656057616662646779687664716969
Rockwell Razors535447565951585154513875634552465151586257504954505454
Voskhod48404848433533364240464142394143394134/3931/4239/4238/3537/4145/3740/4240/5039
Wilkinson Sword
(German)
504548434447414846383236333329362633373637313538252534
Wilkinson Sword
(Gillette)
454438514844473643394040414062373340433547404038453941
7 am
Hi-Platinum
Dorco
ST-300 Platinum
Dorco
ST-301 Stainless
Ladas
Super Stainless
Lord
Super Stainless
Rapira
Stainless Chrome
Rapira
Super Stainless
Rapira
Swedish Super Steel
Schick
Premium
Shark
Super Chrome
Treet
7 Day Platinum
Treet
Classic
Treet
Dura Sharp
Treet
King Super Stainless
Treet
Platinum

 

Click to Vote for the Razor Blades You Would Like to See Tested Next

I will check this poll before I proceed with selecting my next blade for testing and try to pick ones that are generating interest. Please note that you are able to vote for up to 3 razor blades to test.

Vote for the DE Razor Blade You Would Like to See Tested Next! (Vote for up to 3 blades)

Continuing Testing

I will continue to try new blades and will post my findings as I go. If there is a type of blade that you are interested in that is not listed, please contact me and I will track it down and work it into the queue.

Also, it will take me some time to do all the durability testing. If you see a blade listed without complete data that you are eager to see the results, head over to the Razor Blade Sharpness Introduction post and vote for the blades you want to see next!