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Thread: Sharpness of Straight vs DE & SE

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    Absinthe Minded Shavelle's Avatar
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    DE razor blades always pass the hht with ease andja don't even have to strop

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    Electric Razor Aficionado
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    Found the Verhoeven paper, and I misremembered the numbers a bit. He measured the stainless steel Gillette blade at 10,000x power and found the edge varied between 0.35 and 0.45 microns, and the stainless steel solingen straight razor that he measured also had an average edge thickness of 0.40 microns.

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    Senior Member matt321's Avatar
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    Last edited by matt321; 01-25-2009 at 05:03 PM.

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    According to Verhoeven "In the absence of burs, the force required to push a knife through a material is dependent on the sharpening angles and the thickness of the knife blade."

    Given that a DE blade is much thinner than a straight razor immediately behind the honed edge, this alone could account for the feeling that it is easier to cut with a DE even if the blades are both perfectly honed at the same angles. If one accepts this, it also implies something else, but possibly less welcome - of these two equally sharp blades, the straight, which requires more force to push its edge through the hair, is going to be exerting that force on the hair whilst the edge works through the shaft. That would be perceived by the hair follicle as more tugging than from the thinner DE blade requiring less force to pass through the hair shaft.

    At the end of it all, this is interesting but won't change my tool of choice; I like to know when I am being shaved!

    Chris

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    Quote Originally Posted by drmoss_ca View Post
    According to Verhoeven "In the absence of burs, the force required to push a knife through a material is dependent on the sharpening angles and the thickness of the knife blade."

    Given that a DE blade is much thinner than a straight razor immediately behind the honed edge, this alone could account for the feeling that it is easier to cut with a DE even if the blades are both perfectly honed at the same angles. If one accepts this, it also implies something else, but possibly less welcome - of these two equally sharp blades, the straight, which requires more force to push its edge through the hair, is going to be exerting that force on the hair whilst the edge works through the shaft. That would be perceived by the hair follicle as more tugging than from the thinner DE blade requiring less force to pass through the hair shaft.

    At the end of it all, this is interesting but won't change my tool of choice; I like to know when I am being shaved!

    Chris
    Dr. Moss, I see what you're saying but my thoughts are that it might not be that relevant with shaving as all edges are cutting at an angle.

    I really do believe that any pulling sensations the straight imparts are from catching the skin pressure. The coating effect is what inoculates modern blades from this and allows greater pressure when shaving.

    I wish I could remember the article I read some years back that was a from the early part of the twentieth century where the complaints of early DE users are recorded as being that the DE's are not as sharp as straights and "pull". If this is an accurate reflection my theory is this comes from two things: DE's not being coated at that time and too much pressure when shaving. The DE as well as other more modern blades lend themselves to the temptation of applying pressure (though you're definitely not supposed to with a DE) and many people probably did make that mistake just like straight razor users who have not learned proper technique.

    An interesting experiment to test this theory would be for a DE user to get one of those old hones for DE blades off of ebay, hone a blade so that the coatings are removed and then shave with it. It would be ideal if the user was also familiar with straights and could then compare the two.

    Regards,
    EL

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    Quote Originally Posted by drmoss_ca View Post
    According to Verhoeven "In the absence of burs, the force required to push a knife through a material is dependent on the sharpening angles and the thickness of the knife blade."
    That is only true if the object being cut, is bigger than the blade width. Verhoeven was not talking about shaving as such. A hair diameter varies from 50 to 120 microns. As soon as the hair is severed, it doesn't affect the force required to cut any longer. With both DE blades and straight razors the hair is severed long before the cutting bevel has passed, hence the thickness of the blade has no part in that. The only contributing factors are the enclosed angle of the cutting bevel and the refinement of that bevel's tip.

    The simple fact is, most commercial blades are sharpened in a controlled and highly technological environment. Most razors are home honed. Glen, in posses of all the right tools and skills, has the ability of making a razor keener than the average commercial blade. Not all home honers shave with such keen razors. But with more knowledge and tools available than ever before, many straight razor users today match the keenness of commercial blades.

    There are many things in this thread, that I don't agree with. Too many.
    While DE-blades may rust to dullness, I think most razors do not. Many oil their blades, some use stainless steel razors. Those razors do not corrode to dullness.

    Stropping is not abrasive for steel. Maybe for rust, but not for steel. If it was, every strop would start to show black discoloration within one or two months of daily use. CrO loaded strops show such discoloration after very few stroppings. Clean leather does not.

    Those "Popular Science" articles should be approached with caution. The pictures err on optical resolution. The presented facts about disposable blades cannot be transposed just like that to nowadays straight razor edges. During my DE days, I never dried a blade. I rinsed them with cold water and stored them in the bathroom. My razors receive much more care than that.

    Bart.
    Last edited by Bart; 01-31-2009 at 08:05 PM.

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    Quote Originally Posted by Shavelle View Post
    DE razor blades always pass the hht with ease andja don't even have to strop
    my straight razors can pass the HHT in BOTH directions at a variety of angles... and i don't strop either

    also, stainless steel blades should also stain at the very edge. i've never seen it myself but in theory it's the oxidation that protects the steel from further oxidation.
    Last edited by cotdt; 02-01-2009 at 12:22 AM.

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