Illustration of Safety Razor Parameters (Blade Exposure, Guard Span, Blade Gap, Etc.)

Discussion in 'General Shaving Discussion' started by ShavingByTheNumbers, Oct 17, 2017.

    It looks like the best place right now is the blade angle page (link). Should I just replace the picture at the top with my more comprehensive picture? That would be easy. Most of the other pictures there seem to load sometimes and not load other times. A new page could be created under "The DE Shave" section of the Interactive Guide to DE Razor Shaving (link) to focus on the parameters of blade exposure, guard span, etc., but I'm not willing to bother with that right now. I should add that to the list of projects. :001_rolle
     
  1. This is really outstanding work. It is very frustrating to see razors compared by gap, which really tells us very little. This is especially misleading to new shavers trying to find a reasonable fit for their beard and skin. Your diagram on the other hand really illustrates the complex geometry affecting shave quality and aggression. Well done.
     
  2. Thanks, Spang. What you wrote really reminds me of where I started with DE shaving last year. Trying to figure out what to get was a mess. I wanted quantitative data and almost everything was qualitative. In the end, I had to pick something, so I did my best with the available opinions out there. I'm positive that we can help quantify aggressiveness and efficiency with razor measurements and help all new shavers, and even seasoned ones, make better decisions for their beards and skin types.
     
  3. While this all makes for an interesting read, the only real way to know how aggressive or mild a razor is going to be, is to use it. I've seen people say that in their experience, the DE 89 is too aggressive for them while other people say that the R-41 isn't aggressive at all. Ultimately, all the opinions, reviews and feedback on this or any other shaving forum are essentially useless. One's personal experience is all that really counts.
     
  4. Your point about how the same razor feels different to different people is exactly why quantitative data is so valuable. If measurements are available for blade exposure, guard span, and blade angle, and you've figured out what values work best for you based on your personal experience with different razors and their measurements, then you can make informed decisions on what razors to buy that will work best for you. You'd be able to look at a razor and its dimensions and have a very good idea of how it would work for you without ever trying it.
     
  5. Don't agree, with respect. Objective data isn't the only measure, sure, but it helps when you don't have access to the hardware. The ultimate test is always subjective, but as a purchasing aid hard data would be very valuable.

    Edit: directed to @steelheart1948.
     
  6. This very important data and it's analysis
    Presented in this thread is not meant to
    Displace the" YMMV " Phenomenon, but
    Is for the purpose of offering a much
    Needed deeper understanding of the
    Dynamics and engineering of the Safety
    Razor as a tool.
     
  7. You're missing the whole issue here
    What they are presenting here is largely
    Hard Cold Dispassionate Data, not reviews
    Or feedback and up to this point any
    Perceived opinion is solely based
    In the interpretation of the data.
     
  8. Yes, and the surprisingly large variation in blade exposure in commonly available safety razor models, some even having negative blade exposure, makes it especially difficult to reach a conclusion based on any one parameter. But I'll keep reading your posts on this subject and see what conclusions you can reach. And like others here, I'd love to have the kind of information you are developing here before buying and trying more razors.
     
  9. Can I understand if a razor that has a 95 mm gap blade is more aggressive than one with 86mm gap? Thank you
     
  10. Right. Blade exposure is one of the important parameters that would be nice to know when considering a purchase.

    Blade gap is loosely related to aggressiveness, so a razor with a 0.95 mm blade gap may or may not be more aggressive than a razor with a 0.86 mm blade gap. What really matters are blade exposure, guard span, and blade angle because the skin and hair interact with the razor and blade through these parameters. Blade gap generally relates to guard span such that larger blade gaps usually correlate with larger guard spans, but there's no direct relationship.
     
  11. But, theoretically, a razor blade gap of 96 mm is more aggressive than an 86 mm blade?
     
  12. That will usually be the case, I'm sure, but that might be the case for 55 % of the time while razors with a 0.86 mm blade gap would then be more aggressive than razors with a 0.96 mm blade gap for the other 45 % of the time. Those percentages are made up, of course, but they help make the point that it's hard to say whether a particular razor with a 0.96 mm blade gap is more aggressive than a razor with a 0.86 mm blade gap without knowing the important parameters of blade exposure, guard span, and blade angle.
     
  13. For example: Timeless OC 96mm vs Wolfman OC 86mm. What’s the most aggressive?
     
  14. As is clear from my previous responses, no one can say which one is more aggressive just by looking at blade gap. I haven't used either one of those razors, but maybe someone who has used both razors could chime in and give you an opinion. Have you searched B&B or the Internet to see if someone has already made a comparison between those razors?
     
  15. lMHO blade gap is one of
    The most important of the parameters
    And opions on this issue is not a settled
    Consensus. So no matter how convincing
    A point of view concerning razor aggressiveness may be, it is only that
    Person's interpretation of the parameters.
    So yes the .96 increases the agressivenes
    More than the .86 dose
     
    Last edited: Oct 27, 2017
  16. Just to push things to an extreme to show your last sentence isn't quite accurate, if you had and inch (or 2.5 cm) of blade exposure, it wouldn't matter if the gap was .96 or .86, would it? You would essentially have a shavette and not a safety razor. What I most want to know is, how steep or shallow a shaving angle can you use before the safety bar or cap lifts the blade off your face? You can't ignore blade exposure for that.
     
  17. @mozartman: You read my mind. I just put together this little drawing for @weekly to think about:

    upload_2017-10-27_21-52-21.png
     
  18. To confuse the matter further, applying the term 'aggressive' to a razor is somewhat subjective. How aggressive a razor feels depends on parameters beyond the razor, like skin type or beard density for instance. A razor that's aggressive for me is mild for someone else, but these terms don't tell us anything unless we have the same face, technique, lather, etc.

    Part of the process of defining a razors parameters is to define the terminology used. Subjective terms like 'rigid' and 'aggressive' need to be separated from objective terms like 'guard span', 'neutral blade angle' and 'blade exposure'.

    I think the best we could hope to achieve in this discussion is to define correlation - as distinct from causation - between objective measurements and subjective outcomes. Something like "May suits users with a preference for very aggressive razors" for example.

    In summary, @weekly is just as correct as anyone. However, equating subjective outcomes directly to a single objective measurements is also flawed. Perhaps we can agree that without a database of measurements, preferences and information regarding users, making any conclusions about this now is a little pointless.
     
  19. Yes, I've long since learned that hard data and statistics, though highly useful, only take one so far. A scientist or engineer could assign precise, objective definitions to terms like aggressive and rigid, but the outcome on one's face would still not be entirely certain. I was cautioning @weekly against too much reliance on blade gap or any other single measurement, and that was @ShavingByTheNumbers' point too, I think. I don't think anyone is saying you can completely reduce the performance characteristics of even the relatively simple safety razor to a series of numbers, at least not as a practical matter. You can see from his posts that @ShavingByTheNumbers understands that very well.
     

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