Measured Blade Width and Thickness of New vs. Used Blades

Discussion in 'Safety Razor Blades' started by ShavingByTheNumbers, Sep 8, 2016.

  1. On August 25th, I wrote about measuring DE blade width with a digital caliper and a homemade cardstock fixture ([thread]499240[/thread]), and on September 1st, I started a thread about a comprehensive DE razor blade table in the B&B ShaveWiki that would hopefully have enough room for all blade measurement data, including blade width, thickness, etc. ([thread]499764[/thread]):




    Blades are either new or used. Ideally, only new blades should be used for official blade measurements. Used blades might have buildup on them that is hard to eliminate and might affect thickness measurements, for example, and more importantly, used blade width might be a little less than new blade width due to wearing down of the cutting edges. If dimensions do not measurably change by normal use or by time in a blade bank, then used blades could be treated like new blades for official measurements. I was guessing that I wouldn't be able to measure any differences, but I wanted to confirm this guess, so I conducted a small experiment.

    I measured the thicknesses and widths of one new KAI Stainless Steel blade and one new Polsilver Super Iridium blade before using them for 6/7 and 5 shaves, respectively, after which I measured their thicknesses and widths again. Wax spots were thoroughly removed from the Polsilver blade. (KAI blades do not have any wax on them.) Blade thickness was measured first with my digital micrometer, having a resolution of 0.001 mm. Blade width was measured next with my homemade cardstock fixture, to properly hold the blade, and my digital caliper, having a resolution of 0.01 mm. Before measuring the blades, both when new and used, the blades and measuring faces of the digital caliper and digital micrometer were properly cleaned with paper soaked with rubbing alcohol and allowed to dry. Room temperature was very similar during all measurements.

    Here are the thickness and width measurements:

    BladePurchase DateMeasurement DateConditionThicknessWidth
    KAI Stainless Steel2016-07-122016-08-26New0.100 mm22.16 mm
    KAI Stainless Steel2016-07-122016-09-03Used for 6/7 Shaves0.100 mm22.16 mm
    Polsilver Super Iridium2016-07-242016-09-03New0.091 mm21.97 mm
    Polsilver Super Iridium2016-07-242016-09-08Used for 5 Shaves0.091 mm21.97 mm

    As you can see, the width and thickness measurements are identical before and after each blade was used. This was expected, but it was better to confirm the suspicion than operate in the future under an assumption, if used blades are ever to be measured. It is very possible that blade width might measurably decrease with significantly more use, such as when used dozens of times by an Excalibur Club member.

    Given the results here, one could argue that it would be cost-effective to break into blade banks and measure blades that were used normally. I prefer to err on the side of caution and consistency and stick with only new blades as the best practice for collecting official blade dimension measurements. Nevertheless, both new blades and blades that were used normally could be measured and collected together, as long as all pertinent information is noted. Purchase date, for example, is important to record because blade measurements could be found to have changed due to design and/or manufacturing differences. The measurement date and condition of "new" or "used" should be enough for blades that are new and then used normally and measured soon thereafter, but for used blades from a blade bank, it would be preferable for some estimate of when the blade was used to know how long it was sitting around before being measured, but such estimates might be futile and unnecessary.
  2. Very interesting. What is the goal or hypothesis for studying dimensions of spent blades?
  3. jamesspo

    jamesspo Contributor

    I don't think there's any particular plans or hypothesis around old blades. He's just trying to verify the assumption that new and used are dimensionaly equal (at least for the number of shaves on the blades he measured), should that assumption ever need to employed (say because a used blade is all he has on hand for a particular blade type).
  4. Thanks, James. You got it. New blades are preferred for official measurements, but used blades could probably be used without any issues. I would just rather not take any chances with used blades from blade banks, but others might disagree and that's okay if they are willing to do proper measurements and recordkeeping.
  5. You are probably my favorite poster on B&B. I would like to set you up in my reloading room with my Dillon 650 and see where you are at a few hours later. The digital caliper I use in there was less than $50 on Amazon, yours looks much nicer!
  6. Wow! Thanks, Benjamin! What a compliment! I enjoy your posts, too, buddy! :thumbup:

    I had to look up what a Dillon 650 is, which goes to show what I know about guns, but I would get a kick out of that! I've never even gone to a shooting range. I'm up for it, though!

    The digital caliper that I bought is the iGAGING OriginCal 0–6 in. Absolute Origin IP54 Digital Caliper (item number 100-700-06). I got it for $39.95 from Amazon. It's a great caliper for the price, especially with its "absolute origin" accuracy, which is really cool. It's actually modelled to look like a much more expensive Mitutoyo caliper, which I think is considered the best out there, but that's based on what I read. This is my first caliper and I'm really enjoying it. Here is a YouTube video about the iGAGING absolute origin caliper:
  7. jamesspo

    jamesspo Contributor

    Thanks for the pointer on the caliper. I'm always looking for good instruments.

    On the shooting out. You think you have expensive hobbies now... :) Trust me on this. Get out there some time though. Firearms are too fun for words. It's whole new world of mechanical geekdom to explore.
  8. You're welcome for the tip. Glad to help! Regarding the shooting range... Uh oh. Maybe I shouldn't know about that. Ignorance might be bliss. If I get involved, there might be no stopping me. For all I know, you guys might already talk about shaving your ammo. Seriously, I wouldn't be surprised, so yeah, it would be too much fun. :w00t:

Share This Page