View Poll Results: Canvas heats the edge: Fact or Fiction?

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  • Yes, canvas strops heat the edge effectively, and that's why we use them.

    6 13.95%
  • Nah.. it's BS.

    37 86.05%
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  1. #1
    yeehaw. Ben325e's Avatar
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    Default Canvas "heats" the edge: Fact or Fiction?

    I've read it too many times, folks. While we may continue to argue the merits of the canvas strop, let's get this one taken care of NOW. People say "strop a few times on the canvas strop to heat the edge, making it more malleable for the leather to do it's job"...... I think this is BS, too.

    Consider what is being said: 20 or so laps on a canvas strop is enough to bring the temperature of the edge or the razor up high enough that it is actually more pliable for the leather component of your strop. What?!?! That's a load of codswollop.

    Let's think of basic physics and heat transfer here: The area of contact between the razor and the strop is very small, especially in comparison to the entire surface area of the razor and tang. So, as you are swishing your razor along your strop, "building up heat", the entire rest of the razor and tang is being dragged through the air, causing a cooling effect. Try it. Right now. Raise your strop hand in the air, and swish it back and forth the speed and length of your typical strop stroke. Does it feel cooler or warmer than the hand that's not waving around? Unless you're waving your hand in front of a heater duct, it should feel cooler. If not, call your physician.

    Part two: the heat does NOT stay at the edge. With the exception of the uber-cool Seraphim Seramix brand of razors, Straights are made out of metal. Metals conduct heat quite well in comparison to many other materials. So, when that little tiny edge or your razor picks up some heat due to friction, it shares it with it's neighbor. The heat would pass from the edge, through the grind, to the spine, along the tang, and end up in the monkey tail. (that sounds like top notch lyrics to a new kid's song.... from the edge spine through the grind to the spine along the tang and end up in the monkey tail... sing it... it's catchy!)

    If you want to try a cool experiment regarding heat transfer, fill an empty gatorade bottle full of water. Put the cap on and go build a fire in your back yard. Throw the gatorade bottle into the hottest part of the fire. don't worry, it won't melt or burn. As the heat builds up in the plastic, it gets transferred to the water. The water continues to absorb the heat so effectively that the water will boil well before the plastic even thinks about melting. Try to consider how this same principle applies to straight razors and heat transfer away from the edge.

    So, the heat would have to be great enough to not heat the edge, but the entire metal component of your razor, and then maintain a good bit of that heat while you drop the canvas and get the leather. And then we need to think, how many degrees does the temperature need to be raised to make any significant? Well, I for sure can't tell any noticeable difference in the temperature of my razor after using the canvas, so I can assume that it only needs to raise the temperature just a tiny bit. So, would it make more sense for me just to strop while in direct sunlight, or to raise the temp on my thermostat a bit? Would that make my razor sharper and smoother? No.

    If you really want to heat the razor, then get out a 1200 watt hair dryer and blast the razor for a few minutes. it'll be hot, I promise. A lot more effective than a canvas strop. I still don't think it'll be hot enough to make a dang bit of difference in the sharpness of the razor.

    Plus, when stropping, heat is a result of friction. I don't know about the rest of you folks, but I sense a heck of a lot more friction when stropping on latigo leather than I do on the canvas. So, if you wanted to heat the edge via stropping, leather makes much more sense than canvas.


    I think when people say that the canvas "heats" or "warms" the edge or whatever, is just because they are regurgitating what they have read or heard. Don't believe everything you read or hear. If you do happen to be one of the folks who believes everything they read, then let me tell you... your straight razor edges will be MUCH better if you send Ben325e lots of money every month via Paypal. You gotta try it to believe it - it's truly phenomonal.

    It's much more respectful and insightful to tell people the truth. If the canvas works for you (I use mine every time) but you don't know why, then say that. If you have a hypothesis, then say it is.

    I would much rather someone say "I think that stropping with an X pattern is good because it smooths out the sides of the striations left by hone scratch patterns" than to hear them proclaim it like it is the truth. If you don't KNOW something, then don't say it like you do. There are many things that are still mysterious about straight razors, and it's okay if you don't know everything yet.

    So, I'm in the "Canvas heats the edge" is BS camp. Where are you?
    Last edited by Ben325e; 12-29-2008 at 03:58 PM.

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  3. #2
    Senior Member jszabo's Avatar
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    still kind of a newbie gotta think on that one anyone here got a phd in thermodynamic engineering?

  4. #3
    yeehaw. Ben325e's Avatar
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    For those of you who vote yes, I would love to hear your musings on why/how it is effective.

    I'm not saying that the canvas doesn't do something: I use mine everytime. I'm just saying that heat has nothing to do with it.
    Last edited by Ben325e; 12-29-2008 at 04:28 PM.

  5. #4
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    I think the canvas is effective as a "first step" because it does have a higher coefficient of friction than the smooth latigo.

    I did a search one time and came up with an old engineering handbook that discussed belts for use in pulley systems. In descending order of friction it had canvas, then rough side leather, then smooth leather.

    And the important issue is that it is the friction that is burnishing the edge. A 4000 grit hone has a higher coefficient of friction than a 8000 grit hone, and thus you use it first. The 4000 grit hone doesn't pre-heat the edge for the finishing hones, it is simply part of a progression.

    Compared to a hone, canvas is pretty mild, but it does have some small honing action going on. I load mine up with the Dovo white paste, which definitely has some abrasive qualities to it, albiet much less than say Chrome ox, just a nice mild polishing/smoothing/burnishing effect. Under a scope I can see that the white paste leaves slight striations on the bevel edge.

    I have never seen any visible changes to the edge by using simply the smooth latigo. But there is definitely a performance change after smooth leather stropping.

    Thus I hit the canvas first to freshen up the edge (ala a gentle "honing" if you will...), then go the the latigo to smooth it out, or whatever it is that smooth leather does to the edge

    So, I think "edge heating" is BS as well. It is something the guys in the barbershop of oldentimes came up with and somehow that got turned into fact(?).

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  7. #5
    yeehaw. Ben325e's Avatar
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    here's a book I found on the subject: Design of Machine Elements - Google Book Search

    it says that the canvas was impregnated with rubber to increase the coefficient of friction for pulley belts (p.500)

    To find out which has a higher coefficient of friction for your particular belt, place the canvas and leather on a clean counter top. using a downward angle, try to push the leather or canvas. Which is easier to push? For me, Latigo leather trashes the canvas, but my canvas isn't pasted at all.
    Last edited by Ben325e; 12-29-2008 at 04:41 PM.

  8. #6
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    Quote Originally Posted by Ben325e View Post
    here's a book I found on the subject: Design of Machine Elements - Google Book Search

    it says that the canvas was impregnated with rubber to increase the coefficient of friction for pulley belts (p.500)

    To find out which has a higher coefficient of friction for your particular belt, place the canvas and leather on a clean counter top. using a downward angle, try to push the leather or canvas. Which is easier to push? For me, Latigo leather trashes the canvas, but my canvas isn't pasted at all.
    Yeah, the reference I found was something like that one, but an older version, and it seemed to have non-rubberized canvas, just straight canvas....


    How about this for a test of co-efficient of friction: take your leather strop, pull it taught, and make a fist. Now run one of your knuckles up and down the strop lickety-split fast.

    OK?

    Now try the same thing with your cavas strop.....

  9. #7
    yeehaw. Ben325e's Avatar
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    My leather won that one...

    My canvas is indeed rougher, but the leather is more "grabby".... I think maybe we're encountering different strop materials.

    I've always enjoyed your posts and I place weight with your observations, so please don't think I'm trying to say you're wrong. if you say that your canvas is more "grabby" than the leather, then I believe you. I'm just not getting the same results on my side of the monitor.

    EDIT: It depends on the type of tanning on the leather. Oak tanned leather has a much lower C of F, by almost half. See here:http://metalab.uniten.edu.my/~jeffre...Experiment.pdf
    Last edited by Ben325e; 12-29-2008 at 05:44 PM.

  10. #8
    Senior Member jszabo's Avatar
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    like i said im new at this but it does seem like the canvas would heat it some considering how thin the edge is but then again i'm no stropmeister just my .02

  11. #9
    At this point in time... gssixgun's Avatar
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    I think yer splitting hairs on this one.....

    Pun intended

  12. #10
    Senior Member huntmol's Avatar
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    This is a great thread! I've never believed in the heating canvas myth, but I've got an Illinois strop with linen and it does seem to work well enough.
    Maybe the ideal strop has three strips - one canvas, one latigo, and one horsehide!
    Excuse me, I've got an idea to pitch to Tony

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