Razor aggressiveness, particularly of a double-edge razor (DE) is, for the purposes of this article, both a razor’s likelihood to injure skin and its ability to cut hair of longer length. There are three design aspects of double-edge razors that most influence aggressiveness: blade-bar span, safety-guard design and blade exposure.
Defining Razor Aggressiveness
To fully consider the needed aggressiveness of a razor, one must have some understanding of razor design. Let’s take a closer look at each element.
To fully understand blade-edge exposure, one must first be aware of the natural shave plane of a DE.
Recall from your high-school geometry that a plane is a flat, two dimensional surface. The shave plane of a DE is the plane that would just rest simultaneously on the razor’s top cap and safety bar (or safety comb).
Also recall that a plane, when viewed from its edge, looks like a line. So when you view a photo of a DE looking exactly down the edge of the blade, one can represent the shave plane as a line drawn that just touches both the top cap and safety bar or comb. This is drawn in the photo provided of the DE side view.
The relationship of the blade edge to the shave plane determines the blade-edge exposure. If the edge is underneath the shave plane, within the protective cover of the top cap and safety bar/comb, then the blade exposure is negative.
Similarly if the blade edge is above the shave plane, proud of the protective cover of the top cap and safety bar/comb, then the blade exposure is positive. (The down-the-edge photo shows the blade edge at point A above the shave plane.)
A neutral blade exposure is where the blade edge lies at the shave plane.
Shaving Technique And Blade Exposure
If blade exposure is negative or neutral, then for maximum razor aggressiveness while shaving, the razor would be oriented so that the shave plane remains parallel to the skin surface as much as possible. Of course, this is also true for razors with positive blade exposure, but using this maximum-aggressiveness orientation would usually lead to wounds.
So to avoid wounds when shaving, DEs with a large positive blade exposure are usually oriented such that only the top cap or safety bar/comb is touching the skin, but not both simultaneously. This shaving accommodation to avoid wounds from large-positive-blade-exposure razors doesn’t take full advantage of the safety-razor aspect of the instrument, and could be considered an overly-aggressive design that’s generally not needed by most users.
Blade-bar span is defined as the distance between the blade edge and the line of the safety bar/comb that contacts the face. (This is the distance A-B in the down-the-edge-view photo.)
This is slightly different that the blade-bar gap, which is the shortest distance between edge and bar/comb (distance A-C in the down-the-edge photo), and is slightly more easily measured than span, but is less relevant to the shaving character of the DE.
This is because the blade-bar gap is influenced by the safety-bar/comb cross-section contour, while the span indicates the functional distance between edge and bar/comb. Span affects razor aggressiveness in two ways.
Firstly, span influences the length of hair that a DE will cut. The larger the span, the longer the whiskers it will effectively shave. This is because as a DE is drawn across the beard, the safety bar/comb to some degree (depending on its design) will push the hair over as it passes. The larger the span, the more space the hair has to recover toward upright prior to contacting the blade.
Secondly, span influences how much skin can bulge up between bar/comb and blade. Larger spans allow for more skin bulge, which increases the opportunity for the blade to injure delicate dermis. Of course, shaving technique affects skin bulge as well. Very light pressure reduces skin bulge, as does skin stretching.
The design of safety bars/combs affects razor aggressiveness as well. For DEs with teeth or scallops, the width of the teeth/scallops, relative to the gaps between them, is a factor in razor aggressiveness. The larger the guard gaps, the more aggressive the razor, all other things equal.
Safety bar contours matter as well, but their impact on DE razor aggressiveness will vary. Round bars as found on some plastic DEs may remove more lubricant ahead of the edge and possibly might cause hair to lay down more completely when compared to toothed or scalloped designs. Similarly Gillette Tech designs, with the stamped safety bar that has small grooves parallel to the shaving direction may have those ridges to allow more lubricant to remain ahead of the blade, but are as likely to lay hairs down as the round or un-scored safety bars.
More significant are the reverse-toothed safety bars as seen on some slant-bar designs such as the Merkur 37C. (See photo.) The reverse toothing, which points toward the blade rather than away as seen in open-comb DEs, allows longer hair to be cut as well as allowing for more skin bulge. Both of these factors tend to contribute to razor aggressiveness.
Not All Aggressive Razors Are Equivalent
Some DEs are aggressive because of positive blade exposure. Others will allow skin to potentially bulge before the blade by having a large blade-bar span or a safety bar/comb design that is rather open. Some may have all three characteristics.
Adjustable DEs obviously have the advantage of having an adjustable blade-bar span, but it should be noted that this adjustment also slightly alters the blade exposure because as the span is increased, this also slightly changes the angle of the shave plane in relation to the blade, thus increasing the edge position in relation to the shave plane. (Note that this increase in blade-to-shave-plane angle may also adversely impact the comfort of the shave at more aggressive settings.)
So we finally get to the heart of the issue: how aggressive does a razor have to be to address the needs of individual shavers?
Razor Aggressiveness In Relation To Beard Length
Daily Shavers: Although less common than in by-gone days, those who shave every day will only be shaving short stubble, and therefore a large blade-bar gap is not necessary. Similarly an open safety-bar design or an open-comb baseplate is not needed either. But neither are these more-aggressive design characteristics necessarily excluded. What dictates a daily shaver’s choice of razor is blade exposure, shaving technique (razor pressure and skin stretching) and what one’s skin can tolerate. The skin-tolerance options are explained further below.
Long Hair (Infrequent Shavers): Persons who shave infrequently are going to have longer stubble — just the opposite of daily shavers. This longer stubble will likely call for longer blade-bar spans, safety bars that have open designs such as the reverse-toothed pattern on Merkur slants, or open-comb baseplates. Users’ ultimate choice of overall razor design depends, once again, on their skin. The more delicate their skin, the more they will want to consider razors with less positive blade exposure – a mild open-comb razor may be ideal.
Fully-Grown-Beard Removal: If a man has a fully-grown beard and wants to shave it off without first closely trimming it with clippers or scissors, then a straight razor is the best shaving implement. But that’s not a DE (the last time I looked). So the optimal DE option for full-beard removal would be an open-comb DE razor, with small teeth and large gaps between them – all to maximize the capacity of the razor.
Razor Aggressiveness In Relation To Skin Type
Loose Skin versus Tight Skin: If a shaver doesn’t perform skin stretching while making his shaving strokes, then a person with skin that is more loose will likely need a DE with a small blade-bar span as well as a neutral-to-negative blade exposure to minimize the likelihood of skin getting nipped due to bulging before the blade. However, if a person is an infrequent shaver, thus having longer stubble but with loose skin, then a mild-shaving open-comb design with a neutral-to-negative blade exposure may likely be the best option.
Fragile versus Tough Skin: Some persons have relatively fragile skin — more susceptible to injury — either due to genetics or increasing age. Fragile skin will likely call for smaller blade-bar spans, negative blade exposure, or both. People with tougher hide only have to look to stubble length and skin tightness as variables to guide razor-aggression characteristics.
Dense Hair (many follicles concentrated in a given area): Though a sharp blade may be the primary concern to deal with dense hair, DEs with aggressive designs may be helpful to keep the razor from riding up on the hair and thus not shaving as closely. The limiting factor to choosing an aggressive razor in this case would be the characteristics of the user’s skin.
Thick, Tough Hair Follicles: The razor choice in this case is similar to that for dense hair (see the preceding paragraph).
Heavy-handed Shavers: If you just can’t manage a light touch on the razor, then your skin is much more likely to bulge and get nipped by the blade. Clearly safety-bar razors with a small blade-bar span would be called for. Also, irrespective of whether your razor is safety bar or open comb, your razor should have a negative blade exposure.
Daredevils (yeah, you Mr. Macho): If you’re one of those who just have to live life on the edge (pun intended), and you prefer to shave with a DE that threatens at any moment to compel a blood transfusion, then what are you doing considering a DE razor in the first place? Clearly you’re psychologically suited to shave with a straight razor. But if you insist on using a DE, then you’re looking for razors with large blade-bar spans or positive blade exposures or both. Also, most adjustables set to maximum aggression may provide the needed rush.
Razor Sellers And Reviewers Take Note
It’s great for a shaver to understand how DE design aspects apply to a razor’s shave character and how that fits with a user’s needs. However, most razor manufacturers and sellers don’t do an adequate job of providing objective data so that purchasers can infer razor performance without resorting to trial and error.
Also, razor reviewers don’t often provide any objective razor-design information when opining in a forum, blog or seller-site review. They can’t be greatly criticized because it’s nearly impossible to get accurate blade-bar-span measurements (or even blade-bar-gap measurements, which are less useful, but a bit easier to get with a micrometer). It’s also nearly impossible to get accurate measurements of blade exposure, though some key razor-design aspects can be shown qualitatively via enlarged photos of razor heads, when the camera is aimed directly down the blade edge, and a line added showing the shave plane.
So to a large degree it comes back to the manufacturers, who surely must (or should) have data on the key design characteristics of DE razors:
- Blade-bar span (for safety-bar razors, of course)
- Blade exposure
- Blade angle in relation to the shave plane
It is up to prospective buyers to request sellers and manufacturers for this objective data so that they don’t have to keep evaluating razors through trial and error – a process which too often results in purchasing razors not well suited to the buyer’s needs.
Good News: Some Razors’ Aggressiveness Can Be Tuned To Suit
If you have a two-piece or three-piece DE that is not quite right for you – either too aggressive or not aggressive enough – you can easily customize its shave character. TTO razors, because of their fixed space designed to clamp the blade in place, are less amenable to aggression tuning beyond any adjustability intended by the manufacturers.
The simplest method for tuning razor aggression is to use a shim. A shim is a DE blade that has had the cutting edges trimmed off using scissors.
A shim placed between the razor’s cutting blade and the baseplate will make the razor more aggressive. A shim between the cutting blade and the top cap will make the razor less aggressive.
If one shim isn’t sufficient to tune your razor, a second one may be added for more extreme adjustments.
A potential alternative (or addition) to the use of a shim for tuning razors’ aggression is to use tape on the underside of the top cap or on the top of the baseplate as appropriate. Your choice of tape will largely depend on its thickness. The adhesive capability of the tape isn’t terribly important because when in use it will be compressed between the top cap and the baseplate, so it tends to stay in place semi-permanently.
I have experimented using electrical tape, with good results. (See the photo, in which electrical tape has been applied to the underside of the top caps of a 1965 Gillette Tech and a contemporary Lord L.6 razor heads, making both shave slightly less aggressively.) Others have used blue painters’ tape or masking tape. Even clear “magic” tape may be used successfully as a single layer of thin tape for making minor adjustments. Two layers or more of tape may be used as well for larger adjustments.
It should be noted, however, that there is a practical limit to the use of shims or tape for making a razor less aggressive. Adding excessive spacing using shims, tape, or both between the blade and the top cap can have offsetting effects. By moving the top cap farther above the blade edge, the blade exposure does become less positive and thereby less aggressive. However, this same adjustment also increases the top-cap-to-blade span, which has the same effect as increasing the blade-bar span: it tends to make the razor more aggressive because it allows more span in which skin can bulge and get nipped.
Tuning your razor’s aggression with shims, tape, or both is best done judiciously and may require a trial-and-error methodology.
Advice For DE Newcomers
If you’re buying your first DE razor, of course read reviews, study photos and other available information such as this article, and obviously try as much as possible to get the right razor for your beard. However, a two- or three-piece razor may be your best bet because of the option of using shims or tape to tune shaving character in case the razor isn’t quite right for you. Even if the razor is an adjustable type by design, many of these are too aggressive for some users, so a two- or three-piece razor is the more flexible option as opposed to TTO designs, whether adjustable or not.