Open comb vs. Safety Bar Razors: Muhle Comparison

Discussion in 'Double Edged Razors' started by ceebee, Apr 6, 2010.

  1. I recently purchased two new Muhle DE razors. One is the R89 which has a solid scalloped safety bar. The other is the R41 which has a toothed bar a.k.a. open-comb. I was interested in determining how these performed. Using identical blades in both razors, I tried shaving with each, alternating on a nearly daily basis. In other words, if I had a Derby blade in the R89 with 2 shaves on it, I would compare that with the R41 charged with a (different) Derby, also with 2 shaves on it.

    On a subjective level, I found the R41 open comb to be a consistently more aggressive razor than the R89 which I would describe as mild, yet very effective. Both razors are capable of accomplishing a BB smooth shave. That said, the R89 requires a little more operator effort (pressure) and more passes, especially around the jaw line. YMMV.

    When you examine this pair of razors, it is immediately apparent that the blade geometry and exposure are pretty radically different. I’ve tried to illustrate this in the accompanying pix.

    In the R89, the blade is compressed against the curved top plate by a pair of horizontal pillars which are parallel with the long axis of the blade. These pillars are positioned to contact the blade at points which are ~6mm in from an edge. This arrangement results in the production of a distinct curve to the blade (concave downward) as the razor is assembled and tightened, and brings the cutting edge of the blade towards the scalloped safety bar. Using feeler gauges, I measured the gap between the blade edge and the bar when the razor is fully assembled to be 0.029” which is in close agreement with the Wiki tabulation citing a gap of 0.030” { }.

    By comparison, the open-comb Muhle has no horizontally oriented pillars to compress the blade into a concave down curve. Rather, the blade is compressed under a much broader zone between the curved spans of both the top and the bottom plates. The compression zone spans 18mm of the total 22mm edge-to-edge width of the blade. Compression of the central 18mm of the blade produces a small but distinct UPWARD curvature of the exposed 2mm of the blade on each side. This can be described as a mild ducktail bend when looking at the razor head from one end. I’ve tried to illustrate this upwards bend in the lower two pix. It is this upward curvature of the blade edge that produces the gap between the blade edge and the individual teeth of the comb. However, the gap between the blade edge and the teeth of the comb is a mere 0.007” which is only ~25% of the gap on the closed comb R89. If one inspects the 1904 Patent Application of K. Gillette for the safety razor in the Wiki { } you can see that his prototype was also an open comb, and that the blade was compressed in a manner almost identical with the R41---compression extends to nearly the edge of the blade on both sides.

    So, what does all this mean? The short answer is that I don’t fully understand. What appears to be evident, however, is that simple blade “gap” is not what is responsible for the more aggressive behavior of an open comb razor vs. its safety bar counterpart. If gap were the determinant, then the safety bar razor at 0.029” should be ~4x more aggressive than the open comb at 0.007”. I’m thinking that the small but distinct upward curvature of the blade edge somehow contributes to its more aggressive behavior when placed against the skin at the proper angle. Somehow, that translates to more or better blade edge “exposure.” I am interested in what my fellow B&B’ers think on this. What, for example, is the "gap" on other brands of open comb razors? Are they comparable to the R41?
  2. Interesting post, thanks. I agree that it's futile to compare blade gap between an open-comb and closed-comb razor. Similarly, comparison of either with an SE would be meaningless.

    Did you notice that the instruction booklet with the R89 talks about loosening the knob for a more aggressive shave? I haven't yet tried that option myself.
  3. Hmmm.... My razors both came in 100% recycled, eco-friendly brown cardboard boxes with Muhle windmill logo/label on box front and Model label on box ends, but no instruction booklets.
  4. Essentially it says that you can loosen the knob slightly, in order to make the blade gap more aggressive. Gillette used to say the same thing about their razors, I believe - at least until the TTO and adjustable models came along.
  5. Thanks for the write-up, the photos, and triggering RAD.
  6. How does it compare to the New?
  7. Interesting observation. Blade to bar gap isn't the only factor in determining aggressivness. The length of the overall opening between the bar and upper clamp also would affect the aggressivness, as would the "ducktail" at the blade edge. Since our faces are soft and compliant the flesh will actually pucker into those gaps. The harder we press while shaving the more the skin will enter into the gaps and the cut will be more aggressive. Razors with more gap between the bar and clamp will be more sensitive to pressure. If you draw a straight line between the clamp and safety bar and the blade doesn't protrude beyond that line, I would think the razor would be more forgiving of technique variation. The gap length, blade to bar height, and blade protrusion would all affect the aggressivness. Shaving technique and blade sharpness also come into play, which allows us to fine tune a razor to make it work for us. or at least work better. I just purchased a 1920 new improved open comb and gave it a spin. It tore me up pretty good! Lot of weepers, and raw all over. Plenty of burn. I will give the razor a different blade and use very light pressure next time! That was my first experience with an open comb. I also have an EJ Chatsworth 89 that uses the Muhle safety bar head like the one in your picture. It shaves like a dream. Smoooooth. It is fun experimenting with the different razors.
  8. Thanks for your observations, Mitts. If I understood GarageBoy correctly, he was interested in a comparison with the "New" like you have. Can you look at the configuration of the blade up close on that razor w/ magnifying glass to see whethere it too turns upwards? Also, if you have a set of feeler gauges, it would be interesting to see what the gap is on the New. I got my gauges at an auto supply store. They're used to measure the gap in "points" of old style auto ignitions. Thanks again.

  9. I did the blade to safety bar measurements on two Gillette open comb razors. The one I got the rough shave from was actually a "new improved" type. It measured .021". I also have a "new" that I have not shaved with yet. It measured .021 to .023 (variance along the length) I may be able to tune that one up to measure closer, but that may well be within normal tolerance. .002" is not much. Neither of the Gillettes forces the blade into a "ducktail" or reverse curve. The clamp plate just forces the blade over the lower plates contact points rendering nearly a perfect arc. It would seem that in order to force the edge of the blade into a reverse curve the blade would have to be supported under its edge. That support near the edge may take up space under the blade usually occupied by shave cream and hair which may cause clogging. Most DE razors I have used can shave a 2 to 3" long stroke without clogging between rinses. You need some space under the blade to collect the "stuff". Possibly the reversed curve razor you are referring to uses a comb design to turn the razor edge upward which would let the stuff through? Sorry for rambling!
    Last edited: Apr 9, 2010
  10. Sorry for the tardy reply---been off for awhile.

    Now I am officially more perplexed. The Gillette open combs which you measured Mitts have gaps which are in the range of what you expect with a closed comb (safety bar) razor. That 0.021" is fully 3x more than the Muhle. As you and others have commented on this thread, gap isn't the only or main determining factor. That said, why do the gaps in open comb style razors seem to be so variable? It might be helpful if we could get a compilation of gap measurements from B&Bers measuring their own, and listing them like in the Wiki for the safety bar razors.

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