Friday, November 21, 2014

Razor Analysis: Merkur 37 Slant Bar in Detail

Though the blade reveal is constant,
the gap, blade angle (not slant), and
edge exposure vary as one measures
left to right. The constant slant, as
shown, increases the effective sharp-
ness of the blade.
This razor gives me an extremely close shave; I have gotten baby smooth in about two passes. However, I don't use this razor much -- in fact, I keep it in my shave box in my closet rather than in the bathroom cabinet -- because its shaving characteristics are too harsh for my skin.

Of course, as I've written before, the most salient feature of the razor's design is the slant of the blade as pictured at left. The most important thing the slant does is increase the effective sharpness of the blade, which has been explained in more detail in a previous article.

But what, specifically, makes this razor both so formidable but also so threatening?

Using my caliper micrometer, I have taken some measurements of the 37's key design characteristics, which are summarized below in the following table*:
                    Blade Reveal (mm)    Blade Gap (mm)    Blade Angle (deg)   Edge Exposure   
Merkur 37               1.5                   0.8 (L) to 1.3 (R)    33 (L) to 26.5 (R)      +++ (L) to + (R)
Merkur 33               1.3                              1.3                       30 deg                    Negative

* Table Notes:
1) Measurements are difficult to measure precisely -- even with a precise measuring instrument -- so everything should be considered a ballpark estimate.
2) Because the Merkur 37 is a slant-bar design, its blade gap, angle, and exposure vary consistently from one end of the edge to the other. So two measurements are given for each of these design aspects representing the dimension at the extreme ends of the edge, left and right, as indicated.
3) I have included the measurements of the Merkur 33 -- a mild-shaving razor -- for comparison purposes.
4) The edge exposure for the Merkur 37 varies from highly positive (that is, exposed, unprotected by the cove of the top cap and safety bar) at the left end of the blade edge,and slightly positive at the right end of the blade edge.
5) The blade gap is measured from the blade edge to the top of the safety-bar tooth, so the gap from the blade edge to the the bottom of the tooth is significantly larger, thus offering a very large shaving capacity for the hair while maintaining a more moderate gap in which to somewhat reduce the chances of  accidentally nipping skin.
6) All measurements were taken while the razors were fitted with a Personna Lab (blue) blade.
This side view of the left end of the edge shows a large blade
angle of 33 degrees combined with a large positive blade ex-
posure -- both of which would offer a more harsh shave. This
harshness is offset a bit by the smaller blade gap a this end.

The generous blade reveal of 1.5 mm would provide plenty of audible feedback while shaving. Normally this might also contribute to micro vibrations of the blade, which could add a bit of harshness to the shave (theoretically). But because of the likely blade-stiffening twist due to the slant-bar design, the vibrations of the blade for both audible feedback as well as harshness are likely damped, attenuated a bit.

In terms of potential harshness or risk of the shave, the Merkur 37 has varying characteristics as one measures from left to right along the edge. At the left end of the edge, the blade angle of 33 degrees and the significant blade exposure above the shave plane suggest  potential shaving risk. Also at that end, the blade gap, though at its smallest for this razor at about 0.8 mm, is still providing a large shaving capacity due to the upward-toothed design of the safety bar. The small gap (measured at the smallest distance between blade edge and safety-bar tooth) mitigates to a small degree the potential harshness of the blade angle and exposure, but less than it might because the toothed safety bar, which itself offers more shaving capacity, but also greater shaving risk.
The right end of blade (pictured here in side view, of course)
shows milder characteristics: a small blade angle combined
with a smaller positive blade exposure.

The right end of the blade edge has a different story. With mild blade angle (26.5 degrees) and smaller positive blade exposure above the shave plane, this side would be less of a risky shave -- that is until one factored in the larger 1.3 mm blade-bar gap, which offers generous shaving capacity that is, again, enhanced by the toothed design of the bar itself. The right end, therefore, still offers a large shaving capacity, which brings shaving risk with it, but this end still would shave less harshly than the left end because of its smaller blade angle and edge exposure above the shave plane.

The capacity and risk of the 37 slant are also increased by the uncommon scalloped surface of the top cap, which makes it more likely that skin might bulge upward and be nipped by the blade.

So by including some ballpark measurements, they tend to support my previously-published qualitative analysis -- although the numbers probably tell a more extreme story. The measurements and side-view photos lead me to characterize this razor as a potentially more-harsh shaver than I would have done otherwise. It's strengths are shaving capacity and the sharpness-enhancing slant of the blade, but its capability brings risk of nicks and cuts, while its slant characteristics bring potential for harshness and the resulting irritated skin especially near the left end of the blade edge.

This razor is probably best matched against a combination of tough beard and not-too-sensitive, not-too-loose skin. This combination will allow the formidable cutting capacity and close-shaving design to do their work without causing irritation and blood loss.

That's the summary evaluation of the Merkur 37 C slant-bar razor by the (approximate) numbers.

[UPDATE: Next week I'll be posting an article about my most recent shave with this slant razor paired with a new test blade. Stay tuned....]

Happy shaving!


  1. Recently came across your blog and I really enjoy the pics you put up with the gaps, angles, etc measured. Keep it up!

    1. Thanks for the encouragement! Best regards.