The following instructions will enable you to measure the blade gap of any typical safety razor to an accuracy of +/- .001 inch.

These are the results - so far -

=============================================

LIST A [last updated - 04/24/08]

=============================================

GAP in 1/1000's of an inch [ +/- .001 inch ]

new value

15 [.38mm]

16 [.41mm]

17 [.43mm]

18 [.46mm]

19 [.48mm] Ming Sui

20 [.51mm]

21 [.53mm]

22 [.56mm]

23 [.58mm] Gillette TECH

24 [.61mm]

25 [.64mm] Gillette NEW

26 [.66mm] SS Red Tip

27 [.69mm] US & English ARISTOCRATs

28 [.71mm]

29 [.74mm] Feather Portable

30 [.76mm]

31 [.79mm]

32 [.81mm]

33 [.84mm]

34 [.86mm]

35 [.89mm]

36 [.91mm] Slim Adjustable @ 7

37 [.94mm]

38 [.97mm]

39 [.99mm]

40 [1.02mm]

========================================

[I'm sorry this post turned out to be a little on the - l o n g s i d e - it will take about 7-8 minutes to read. The process described is much more simple than it appears and in practice you can determine the gap of a razor in less time than it takes to read these instructions.]

Question:

Why would anyone care what the measurement of a razor's blade gap is?

Answer:

If you know their blade gap sizes you can rank razors more precisely by what is often referred to as "aggression".

Being able to compare the "aggression" of various razors, you could then make more reasoned adjustments in shaving technique and better choices when selecting a razor.

&

=================

IDEA !!!

=================

If we could find a few

"computer & camera cowboys" with "big razor ranches",

(who were looking for an excuse to play with their toys),

we could get blade gap measurements replicated/verified

and create a comprehensive table of relative blade gap measurements.

=============================

Background:

Here's the trick ...

Imagine I have a photograph showing myself standing by a tree.

My image, in the picture, measures only 1 inch (head to foot).

The tree, in the picture, is 2 inches from it's highest branch to the ground.

I know my "actual" height is 6 feet.

Since the tree, in the picture, is 2 inches = 2x taller than me, in the picture,

the tree must be 2x6 feet in reality or 12 feet tall.

Now imagine that same photograph is on my computer screen and I zoom in (or magnify it) by a factor of 72.

Because everything in the picture is now 72 times bigger - my on screen height now appears to be 72 x 1 inch or "actual life size" (6 feet head to foot).

My image is now much too big to be contained entirely on the screen but if I scroll to the part of the image where my belt appears, I could measure it on the screen "directly".

If my belt is 1 inch wide on the screen, I know the belt I was wearing when the picture was taken was 1 inch wide.

This is the trick that makes it possible to measure the blade gap of any safety razor.

If you measure a razor's safety bar and it is say 1.5 inches long and you take a picture of that razor straight on, you can magnify that picture using a computer and display it on the screen.

If you magnify the image such that the head of the razor almost fills the screen the safety bar will appear to be about 12 inches long (x8 larger).

The blade gap then will then be less than 1/4 inch (too small to measure accurately).

If you further magnify the image another 4 times the safety bar is now 8x4 = 32 times larger.

[32 x 1.5 inches = 48 inches]

The head of the razor, on the screen, will appear as if it were 4 feet long and the gap on the screen will be almost 1 inch wide. That gap is now easily measured with some precision.

The "on screen gap" measurement

divided by the magnification

is the actual razor gap size.

=====

So how do I do it? you ask ...

To determine the blade gap of a razor - the steps are 4 and all fairly "easy":

1) Measure the length of the safety bar of the razor.

2) Take a photograph of the razor.

3) Using a computer and a photo manipulation program, measure a "magnified" image of the safety bar and the gap on the screen.

4) Calculate the actual size of the gap.

What do I need?

a) 2 rulers,

- one long enough to measure the width of your screen [12 - 15 inches] with markings of 1/16 of an inch

- a second ruler [6 inches] with finer markings of 1/32 of an inch.

b) a digital camera that can focus on an object "close up" at a distance if less than 8 inches from the lens

c) a computer with software that can zoom in and out to resize your photo on screen

d) a calculator

TIME REQUIRED:

To calculate the gap of a single razor - AFTER YOU'VE DONE A FEW - is a matter of only a few minutes.

The first few times through the process, however, will take a little longer.

["EXAMPLE:" measurement values that follow are of a newer sample Gillette TECH safety razor]

=========

STEP 1: Measure the safety bar of the razor and convert that length to thousandth's of an inch.

=========

With a ruler measure the safety bar of the razor to an accuracy of at least 1/32 inch. (You can use calipers if you have them but it is not required). The result will typically be a little greater than 1 1/2 inches.

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EXAMPLE:

a Gillette TECH's safety bar is measured to be ... 1 and 39/64 inches long so it is 1.609 inches long

(39 divided by 64 = 0.609375 plus 1 inch = 1.609)

*** This is value La = 1.609 inch ***

Tip: Fractions of an inch in 1/1000's are easy - with a calculator ...

1/64 = 1 divided by 64 = 0.0156 = 0.016

1/32 = 1 divided by 32 = 0.03125 = 0.031

1/16 = 1 divided by 16 = 0.0625 = 0.063

1/8 = 1 divided by 8 = 0.125

5/32 = 5 divided by 32 = 0.15625 = 0.156

39/64 = 39 divided by 64 = 0.609375 = 0.609

etc ...

=========

STEP 2: Take a digital photo of the razor.

=========

I hold the camera with my right hand and the razor in my left and found no tripod was required if there was bright daylight (or even normal artificial light available).

Take a picture of the razor WITH A BLADE INSERTED - as close to the lens as your camera can focus - so the head of the razor is as big as possible (but still remains completely contained in the picture).

At a distance of 12 inches or more the razor's image will probably be too small for good results ...

The picture above was taken with the razor about 12 inches from the camera.

You can see that with a 5x magnification the gap is not big enough to me measured with precision.

Try to get a picture more like this ...

The above was taken at a distance of 4 inches and the razor head takes up a much greater portion of the picture.

At 5x magnification, the gap is now much easier to see and measure.

Tips:

- No flash is used. Natural daylight is best and should come from behind you.

- Try to get the camera to look directly into the gap between the blade and the safety bar.

The difference between the razor being perfectly vertical (top of blade slightly visible) or tilted slightly away from the camera (so only the blade edge is seen) makes less than a 0.001 inch difference and will not significantly effect the final results.

- take several shots so you increase your chance of getting a good sharp "straight on" result

=========

STEP 3: Computer magnification and on screen measurement of safety bar and gap.

=========

Upload your pictures from your camera to the computer and then ...

a) select the best - sharpest - shot looking "straight on" the razor gap.

The above picture shows the advantage of lighting coming from behind.

With magnification - even when the lighting is not ideal - the gap is easily measured.

b) zoom or resize your best pic - such that the razor head is as big as posssible on the screen yet remains completely visible.

Measure the safety bar "on screen" length

EXAMPLE:

Safety bar on screen = 12 1/4 inches = 12.250 inches

*** This is value Lb = 12.250 inch ***

c) Make NOTE of the reduction/magnification factor used in previous step b). It may range from 25% to 200% depending on your camera, computer screen and software.

EXAMPLE:

150%

*** This is value Ma = 150% ***

d) zoom or resize the screen image upward so the blade gap about 3/4 to 1 inch.

Tip: Use simple multiples to make it easier to calculate the magnification factor.

Make NOTE of the magnification factor used.

EXAMPLE:

450%

*** This is value Mb = 450% ***

If the original shot is zoomed up by 150% as in c) to get razor head all on screen and then further zoomed up to 450% in d) to enlarge the blade gap for measuring this would result in a "MAGNIFICATION FACTOR" of 3x

[Mb / Ma]

450 / 150 = 3

*** This is value Mc = 3 ***

e) measure the gap on the screen and express it to 1/1000ths of an inch

EXAMPLE:

9/16 inch = 0.5625 = 0.563 inch

*** This is value Ga = 0.563 inch ***

=========

STEP 4: Finally - Calculate the actual size of the gap.

=========

You're nearly done!

a) first calculate the size of the magnified safety bar

Multiply the MAGNIFICATION FACTOR [Mc] from Step 3d

x

the on screen safety bar measurement [Lb] from Step 3b

EXAMPLE: Mc x Lb

3 x 12.250 = 36.75 inches

*** This is value Lc = 36.75 inches ***

b) The "Payoff"

Calculate the actual gap size

Multiply the actual safety bar length from Step 1

x

the on screen magnified gap measurement from Step 3e

then divide by the "magnified screen" safety bar length from Step 4a

La x Ga / Lc

EXAMPLE:

1.609 x 0.563 / 36.75

Final calculated result = 0.0246494

so ...

the ACTUAL BLADE GAP is 0.025 inches +/- .001 inch

==================================

If you do everything right, the "gap" result - for any given safety razor - will be between 15 and 50 (1/1000's of an inch) and probably "close" to the values in the LIST B below.

==================================

Here is the tentative start (LIST A) of what I hope will become a comprehensive list of MEASURED razor gaps.

I currently have access to only 6 razors and LIST A contains my results using the method described in this post.

As you can see I could use some help filling in the "gaps"

A very generous forum member who lives nearby has offered to lend to me some razors from his collection for measurement and photographing so "stay tuned".

With a little luck this information will be updated soon.

=======

LIST A [last updated - 04/24/08] *** SEE CURRENT UPDATED VALUES AT THE START OF THIS POST ***

=======

GAP in 1/1000's of an inch [ +/- .001 inch ]

15

16

17

18

19 Ming Sui

20

21

22

23 Gillette TECH

24

25 Gillette NEW

26 SS Red Tip

27 US & English ARISTOCRATs

28

29 Feather Portable

30

31

32

33

34

35

36 Slim Adjustable @ 7

37

38

39

40

=================

The next data (LIST B) was compiled from a survey of comments and "subjective" comparisons posted on this and other shaving forums.

*** Note: These are only "GUESS-timates" and while they may be useful as a guide to indicate that a measurement is "in the ball park" they NEED TO BE VERIFIED by actual measurement ***

======

LIST B [last updated - 04/23/08]

======

ESTIMATED

GAP in 1/1000's of an inch [ +/- .001 inch ]

15

16 Gillette ADJUSTABLE @ 1

17

18

19 Gillette ADJUSTABLE @ 2, Weishi, Ming Sui

20

21

22 Gillette ADJUSTABLE @ 3

23 Gillette TECH, Star

24 SS BLUE Tip, Merkur HD/38C

25 Gillette ADJUSTABLE @ 4, Gillette NEW

26 SS SILVER/TAN Tip, Gillette OLD "BIG FELLOW"

27 US & English ARISTOCRATs

28 Gillette ADJUSTABLE @ 5, Gillette "Old" TECH, PRESIDENT, 58TV SPECIAL

29 Feather Portable

30 SS RED Tip

31 Gillette ADJUSTABLE @ 6

32 Gillette "New Improved", Parker 22r

33

34 Gillette ADJUSTABLE @ 7

35

36

37 Gillette ADJUSTABLE @ 8

38

39

40 Gillette ADJUSTABLE @ 9, Merkur FUTUR @ 6

=================

Additional razors of interrest that might be added to the above lists:

Merkur 1904, PROGRESS & VISION, SLANT etc

Feather Popular

Shicks

Lords

Parkers

misc. "Disposable" razors

injectors

antiques

etc etc etc ...

These are the results - so far -

=============================================

LIST A [last updated - 04/24/08]

=============================================

GAP in 1/1000's of an inch [ +/- .001 inch ]

new value

15 [.38mm]

16 [.41mm]

17 [.43mm]

18 [.46mm]

19 [.48mm] Ming Sui

20 [.51mm]

21 [.53mm]

22 [.56mm]

23 [.58mm] Gillette TECH

24 [.61mm]

25 [.64mm] Gillette NEW

26 [.66mm] SS Red Tip

27 [.69mm] US & English ARISTOCRATs

28 [.71mm]

29 [.74mm] Feather Portable

30 [.76mm]

31 [.79mm]

32 [.81mm]

33 [.84mm]

34 [.86mm]

35 [.89mm]

36 [.91mm] Slim Adjustable @ 7

37 [.94mm]

38 [.97mm]

39 [.99mm]

40 [1.02mm]

========================================

[I'm sorry this post turned out to be a little on the - l o n g s i d e - it will take about 7-8 minutes to read. The process described is much more simple than it appears and in practice you can determine the gap of a razor in less time than it takes to read these instructions.]

Question:

Why would anyone care what the measurement of a razor's blade gap is?

Answer:

If you know their blade gap sizes you can rank razors more precisely by what is often referred to as "aggression".

Being able to compare the "aggression" of various razors, you could then make more reasoned adjustments in shaving technique and better choices when selecting a razor.

&

=================

IDEA !!!

=================

If we could find a few

"computer & camera cowboys" with "big razor ranches",

(who were looking for an excuse to play with their toys),

we could get blade gap measurements replicated/verified

and create a comprehensive table of relative blade gap measurements.

=============================

Background:

Here's the trick ...

Imagine I have a photograph showing myself standing by a tree.

My image, in the picture, measures only 1 inch (head to foot).

The tree, in the picture, is 2 inches from it's highest branch to the ground.

I know my "actual" height is 6 feet.

Since the tree, in the picture, is 2 inches = 2x taller than me, in the picture,

the tree must be 2x6 feet in reality or 12 feet tall.

Now imagine that same photograph is on my computer screen and I zoom in (or magnify it) by a factor of 72.

Because everything in the picture is now 72 times bigger - my on screen height now appears to be 72 x 1 inch or "actual life size" (6 feet head to foot).

My image is now much too big to be contained entirely on the screen but if I scroll to the part of the image where my belt appears, I could measure it on the screen "directly".

If my belt is 1 inch wide on the screen, I know the belt I was wearing when the picture was taken was 1 inch wide.

This is the trick that makes it possible to measure the blade gap of any safety razor.

If you measure a razor's safety bar and it is say 1.5 inches long and you take a picture of that razor straight on, you can magnify that picture using a computer and display it on the screen.

If you magnify the image such that the head of the razor almost fills the screen the safety bar will appear to be about 12 inches long (x8 larger).

The blade gap then will then be less than 1/4 inch (too small to measure accurately).

If you further magnify the image another 4 times the safety bar is now 8x4 = 32 times larger.

[32 x 1.5 inches = 48 inches]

The head of the razor, on the screen, will appear as if it were 4 feet long and the gap on the screen will be almost 1 inch wide. That gap is now easily measured with some precision.

The "on screen gap" measurement

divided by the magnification

is the actual razor gap size.

=====

So how do I do it? you ask ...

To determine the blade gap of a razor - the steps are 4 and all fairly "easy":

1) Measure the length of the safety bar of the razor.

2) Take a photograph of the razor.

3) Using a computer and a photo manipulation program, measure a "magnified" image of the safety bar and the gap on the screen.

4) Calculate the actual size of the gap.

What do I need?

a) 2 rulers,

- one long enough to measure the width of your screen [12 - 15 inches] with markings of 1/16 of an inch

- a second ruler [6 inches] with finer markings of 1/32 of an inch.

b) a digital camera that can focus on an object "close up" at a distance if less than 8 inches from the lens

c) a computer with software that can zoom in and out to resize your photo on screen

d) a calculator

TIME REQUIRED:

To calculate the gap of a single razor - AFTER YOU'VE DONE A FEW - is a matter of only a few minutes.

The first few times through the process, however, will take a little longer.

["EXAMPLE:" measurement values that follow are of a newer sample Gillette TECH safety razor]

=========

STEP 1: Measure the safety bar of the razor and convert that length to thousandth's of an inch.

=========

With a ruler measure the safety bar of the razor to an accuracy of at least 1/32 inch. (You can use calipers if you have them but it is not required). The result will typically be a little greater than 1 1/2 inches.

EXAMPLE:

a Gillette TECH's safety bar is measured to be ... 1 and 39/64 inches long so it is 1.609 inches long

(39 divided by 64 = 0.609375 plus 1 inch = 1.609)

*** This is value La = 1.609 inch ***

Tip: Fractions of an inch in 1/1000's are easy - with a calculator ...

1/64 = 1 divided by 64 = 0.0156 = 0.016

1/32 = 1 divided by 32 = 0.03125 = 0.031

1/16 = 1 divided by 16 = 0.0625 = 0.063

1/8 = 1 divided by 8 = 0.125

5/32 = 5 divided by 32 = 0.15625 = 0.156

39/64 = 39 divided by 64 = 0.609375 = 0.609

etc ...

=========

STEP 2: Take a digital photo of the razor.

=========

I hold the camera with my right hand and the razor in my left and found no tripod was required if there was bright daylight (or even normal artificial light available).

Take a picture of the razor WITH A BLADE INSERTED - as close to the lens as your camera can focus - so the head of the razor is as big as possible (but still remains completely contained in the picture).

At a distance of 12 inches or more the razor's image will probably be too small for good results ...

The picture above was taken with the razor about 12 inches from the camera.

Try to get a picture more like this ...

The above was taken at a distance of 4 inches and the razor head takes up a much greater portion of the picture.

Tips:

- No flash is used. Natural daylight is best and should come from behind you.

- Try to get the camera to look directly into the gap between the blade and the safety bar.

The difference between the razor being perfectly vertical (top of blade slightly visible) or tilted slightly away from the camera (so only the blade edge is seen) makes less than a 0.001 inch difference and will not significantly effect the final results.

- take several shots so you increase your chance of getting a good sharp "straight on" result

=========

STEP 3: Computer magnification and on screen measurement of safety bar and gap.

=========

Upload your pictures from your camera to the computer and then ...

a) select the best - sharpest - shot looking "straight on" the razor gap.

The above picture shows the advantage of lighting coming from behind.

b) zoom or resize your best pic - such that the razor head is as big as posssible on the screen yet remains completely visible.

Measure the safety bar "on screen" length

EXAMPLE:

Safety bar on screen = 12 1/4 inches = 12.250 inches

*** This is value Lb = 12.250 inch ***

c) Make NOTE of the reduction/magnification factor used in previous step b). It may range from 25% to 200% depending on your camera, computer screen and software.

EXAMPLE:

150%

*** This is value Ma = 150% ***

d) zoom or resize the screen image upward so the blade gap about 3/4 to 1 inch.

Tip: Use simple multiples to make it easier to calculate the magnification factor.

Make NOTE of the magnification factor used.

EXAMPLE:

450%

*** This is value Mb = 450% ***

If the original shot is zoomed up by 150% as in c) to get razor head all on screen and then further zoomed up to 450% in d) to enlarge the blade gap for measuring this would result in a "MAGNIFICATION FACTOR" of 3x

[Mb / Ma]

450 / 150 = 3

*** This is value Mc = 3 ***

e) measure the gap on the screen and express it to 1/1000ths of an inch

EXAMPLE:

9/16 inch = 0.5625 = 0.563 inch

*** This is value Ga = 0.563 inch ***

=========

STEP 4: Finally - Calculate the actual size of the gap.

=========

You're nearly done!

a) first calculate the size of the magnified safety bar

Multiply the MAGNIFICATION FACTOR [Mc] from Step 3d

x

the on screen safety bar measurement [Lb] from Step 3b

EXAMPLE: Mc x Lb

3 x 12.250 = 36.75 inches

*** This is value Lc = 36.75 inches ***

b) The "Payoff"

Calculate the actual gap size

Multiply the actual safety bar length from Step 1

x

the on screen magnified gap measurement from Step 3e

then divide by the "magnified screen" safety bar length from Step 4a

La x Ga / Lc

EXAMPLE:

1.609 x 0.563 / 36.75

Final calculated result = 0.0246494

so ...

the ACTUAL BLADE GAP is 0.025 inches +/- .001 inch

==================================

If you do everything right, the "gap" result - for any given safety razor - will be between 15 and 50 (1/1000's of an inch) and probably "close" to the values in the LIST B below.

==================================

Here is the tentative start (LIST A) of what I hope will become a comprehensive list of MEASURED razor gaps.

I currently have access to only 6 razors and LIST A contains my results using the method described in this post.

As you can see I could use some help filling in the "gaps"

A very generous forum member who lives nearby has offered to lend to me some razors from his collection for measurement and photographing so "stay tuned".

With a little luck this information will be updated soon.

=======

LIST A [last updated - 04/24/08] *** SEE CURRENT UPDATED VALUES AT THE START OF THIS POST ***

=======

GAP in 1/1000's of an inch [ +/- .001 inch ]

15

16

17

18

19 Ming Sui

20

21

22

23 Gillette TECH

24

25 Gillette NEW

26 SS Red Tip

27 US & English ARISTOCRATs

28

29 Feather Portable

30

31

32

33

34

35

36 Slim Adjustable @ 7

37

38

39

40

=================

The next data (LIST B) was compiled from a survey of comments and "subjective" comparisons posted on this and other shaving forums.

*** Note: These are only "GUESS-timates" and while they may be useful as a guide to indicate that a measurement is "in the ball park" they NEED TO BE VERIFIED by actual measurement ***

======

LIST B [last updated - 04/23/08]

======

ESTIMATED

GAP in 1/1000's of an inch [ +/- .001 inch ]

15

16 Gillette ADJUSTABLE @ 1

17

18

19 Gillette ADJUSTABLE @ 2, Weishi, Ming Sui

20

21

22 Gillette ADJUSTABLE @ 3

23 Gillette TECH, Star

24 SS BLUE Tip, Merkur HD/38C

25 Gillette ADJUSTABLE @ 4, Gillette NEW

26 SS SILVER/TAN Tip, Gillette OLD "BIG FELLOW"

27 US & English ARISTOCRATs

28 Gillette ADJUSTABLE @ 5, Gillette "Old" TECH, PRESIDENT, 58TV SPECIAL

29 Feather Portable

30 SS RED Tip

31 Gillette ADJUSTABLE @ 6

32 Gillette "New Improved", Parker 22r

33

34 Gillette ADJUSTABLE @ 7

35

36

37 Gillette ADJUSTABLE @ 8

38

39

40 Gillette ADJUSTABLE @ 9, Merkur FUTUR @ 6

=================

Additional razors of interrest that might be added to the above lists:

Merkur 1904, PROGRESS & VISION, SLANT etc

Feather Popular

Shicks

Lords

Parkers

misc. "Disposable" razors

injectors

antiques

etc etc etc ...

Last edited by a moderator: Feb 7, 2017