Does blade exposure matter?

[crleftwich]

I’m going to guess the answer to the question is “yes”, but why?
Does the amount of exposed blade matter in a DE? What’s too much? What’s not enough? What’s just right?

Enlighten me, shaved ones.

 

[emwolf]

I'm going to follow this. I want to know more about the science side of shaving

 

[jmudrick]

First, let's establish definition. A lot of people confuse blade exposure , which matters a lot, with cap span which matters not so much in and of itself. See the handy diagram. Exposure measures the extent to which the blade edge extends beyond the shaving plane. Cap span is simply how much blade sticks out from the cap.

Razors with a lot of negative exposure require pressure to maintain consistent contact with skin. Razors with a lot of positive exposure require great care not to exert pressure which will easily dig the exposed edge into your cheek. See Ikon 104 Tech.

Generally speaking, most prefer somewhere close to neutral. I use razors across the entire spectrum so I guess it "matters" only to the extent that you shave somewhat differenty when the razor is the Ikon 104 vs a Mamba 38. I have seen .04mm quoted somewhere in a Gillette referenced study as optimum from their perspective at one point in time.

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[noodles hovar]

I would think that more blade exposure can result in more profound cuts when technique slips.

Otherwise, I don't know if the unsharpened metal being present makes a difference.

 

[Toothpick]

Not to me. I don’t spend time worrying about anything really. I just load up a blade in whatever razor I feel like using and go to town. Imagine how boring B&B would be if everyone was like me!

 

[hydro-magic]

It matters to me quite a bit. Blade exposure is the thing that makes a razor aggressive or not in my opinion. Too much blade exposure tends to give me irritation. I can use very aggressive razors with good results but I have to really watch the pressure or find other ways to moderate the blade's contact with my skin. With an R41 for example, I can use a steep angle by letting the baseplate comb ride against my skin and honestly get great shaves that way most of the time. A momentary lapse can give me some irritation though. With other aggressive razors "letting the weight of the razor do the work" would be far too much pressure for me. IMO you have to approach them like using a shavette. Try to remove the lather with as little skin contact as possible - absolutely no pressure. If you're a one-pass shaver, a razor with some blade exposure can give a pretty decent quick shave.

For me, a razor with less blade exposure gives worry free comfortable shaves but sometimes at the expense of closeness. They tend to be pretty sensitive to the angle you use though and once you get that mastered, a razor with low blade exposure can still give a close shave.

 

[FireDragon76]

With some SE razors the blade can be more or less recessed and this changes where the blade is cutting relative to the shaving plane. Typically, sensitive skin versions of shavers have recessed blades.

I don't think this matters as much with DE razors that aren't very aggressive and/or you aren't riding the bar.

I would think that more blade exposure can result in more profound cuts when technique slips.

Otherwise, I don't know if the unsharpened metal being present makes a difference.

I would think it would tend to correlate with a more aggressive razor, though not necessarily more effective..

 

[jmudrick]

It matters to me quite a bit. Blade exposure is the thing that makes a razor aggressive or not in my opinion. Too much blade exposure tends to give me irritation. I can use very aggressive razors with good results but I have to really watch the pressure or find other ways to moderate the blade's contact with my skin. With an R41 for example, I can use a steep angle by letting the baseplate comb ride against my skin and honestly get great shaves that way most of the time. A momentary lapse can give me some irritation though. With other aggressive razors "letting the weight of the razor do the work" would be far too much pressure for me. IMO you have to approach them like using a shavette. Try to remove the lather with as little skin contact as possible - absolutely no pressure. If you're a one-pass shaver, a razor with some blade exposure can give a pretty decent quick shave.

For me, a razor with less blade exposure gives worry free comfortable shaves but sometimes at the expense of closeness. They tend to be pretty sensitive to the angle you use though and once you get that mastered, a razor with low blade exposure can still give a close shave.

I have witnessed a pretty common arc of user preference as experience increases, with newer shavers often seeking out more aggressive razors once they have confidence they won't hurt themselves, and believing that they will get closer shaves that way....then after a year of two swinging back the other way after figuring out that it's really a lot about technique, and that most skilled daily shavers can do just fine without massive blade gaps or extreme exposures.

 

[BigJ]

First, let's establish definition. A lot of people confuse blade exposure , which matters a lot, with cap span which matters not so much in and of itself. See the handy diagram. Exposure measures the extent to which the blade edge extends beyond the shaving plane. Cap span is simply how much blade sticks out from the cap.

Razors with a lot of negative exposure require pressure to maintain consistent contact with skin. Razors with a lot of positive exposure require great care not to exert pressure which will easily dig the exposed edge into your cheek. See Ikon 104 Tech.

Generally speaking, most prefer somewhere close to neutral. I use razors across the entire spectrum so I guess it "matters" only to the extent that you shave somewhat differenty when the razor is the Ikon 104 vs a Mamba 38. I have seen .04mm quoted somewhere in a Gillette referenced study as optimum from their perspective at one point in time.

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+1!! Establishing definitions is critical here!

IMO blade exposure is but one component determining how a razor shaves.

In addition to the factors in this diagram, another key factor is how rigidly the blade is clamped.

 

[BigJ]

I have witnessed a pretty common arc of user preference as experience increases, with newer shavers often seeking out more aggressive razors once they have confidence they won't hurt themselves, and believing that they will get closer shaves that way....then after a year of two swinging back the other way after figuring out that it's really a lot about technique, and that most skilled daily shavers can do just fine without massive blade gaps or extreme exposures.

Great point! This pretty much summarizes my history.

These days I get great shaves with razors in mild/moderate range!!

 

[Schnitzel52]

Thank you.
An excellent post.

 

[crleftwich]

First, let's establish definition. A lot of people confuse blade exposure , which matters a lot, with cap span which matters not so much in and of itself. See the handy diagram. Exposure measures the extent to which the blade edge extends beyond the shaving plane. Cap span is simply how much blade sticks out from the cap.

Thanks for the information and clarification. So, I was talking about cap span then.

 

[jmudrick]

Thanks for the information and clarification. So, I was talking about cap span then.

Right, I thought that might be the case.


Cap span matters indirectly because when you increase cap span by narrowing the cap you will also increase exposure if the guard remains unchanged. Thus Fatip and Muhle both increased cap width while leaving the plate relatively (not entirely) unchangedand thereby decreased exposure and made the R41 and Piccolo/Grande less aggressive . They also could have modified the guard geometry to do the same thing.

How much cap span matters directly is somewhat controversial. Clearly with a rigid SE it matters not at all as the blade does not flex with upward pressure of the kind occuring in the normal course of shaving. There are lots of vintage razors with no caps and they shave fine. A thin DE blade does respond to smaller forces applied in shaving and thus pressure in both directions will cause some disturbance in the blades contact. How much flex is induced my increasing cap span isn't clear but certainly in theory there would be less flex likely with tiny amount of cap span than with a great amount all else beIng equal , but with a firmly clamped blade the difference small differences might not be felt much depending on other factors in geometry and shaving conditions (and blade design).

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[emwolf]

is there a wiki table of measurements for various "popular" razors for cap span, blade exposure, etc? That would be interesting.

 

[Raven Koenes]

I want to feel the blade, so yes exposure matters.

 

[naughtilus]

Positive blade exposure is beneficial for slicing a lot of stubble with fewer passes. Negative blade exposure is more adequate for a hysteresis method - slow gradual reduction with higher quantity of passes or buffing (that's how carts work).

 

[kingfisher]

Positive blade exposure is beneficial for slicing a lot of stubble with fewer passes. Negative blade exposure is more adequate for a hysteresis method - slow gradual reduction with higher quantity of passes or buffing (that's how carts work).

Even a razor with negative blade exposure can be efficient if the user applies more pressure. Skin is flexible.

I think blade exposure is one of the most important determinants of the comfort/smoothness of a razor, particularly for shavers with less experience (less blade exposure=generally more comfortable shaving). Having said that, I shave with a shavette, which technically has an infinite blade exposure, and my shaves are smooth and comfortable, so I think any amount of blade exposure can be handled if technique is adjusted appropriately.

Cap span is also probably somewhat important because of blade rigidity issues (as mentioned above in this thread).

 

[RayClem]

There are lots of things that determine how a DE razor shaves. Although blade gap and blade exposure are the ones most discussed, all of the measurements shown in the head diagram can affect the shaving experience.

 

[jmudrick]

is there a wiki table of measurements for various "popular" razors for cap span, blade exposure, etc? That would be interesting.

A few manufacturers post exposure numbers (Karve comes to mind) but most don't and it's quite difficult to measure and ensure consistency so no I don't think we have any exposure database. Blade gap charts are out there yes.

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[naughtilus]

Even a razor with negative blade exposure can be efficient if the user applies more pressure. Skin is flexible.

True, but to an extent. Unless you're Stretch Armstrong there'll be a point where regardless how much pressure you apply, stubble isn't getting cut closer. This is where blade gap comes into play. Negative exposure and huge gap means you can really tuck a lot of skin under the blade. At this point one has to wonder if this is the proper way to shave, instead of getting razor with more blade exposure.