What is aggressiveness?The aggressiveness of a razor largely relies on 5 different factors.
- Blade gap
- Blade angle in the razor
- Razor weight
- Distribution of the weight. (Heavy head/light handle vs. all heavy.)
- Blade angle applied by the user
The last point can influence the shave drastically if not done properly. A user shouldn't follow a quest to find the mildest or most aggressive razor. What a user should do is find the right level of aggressiveness for themselves.
What causes aggressiveness?Razor aggressiveness depends on a variety of factors, the two most important of which are blade gap and weight. The larger the blade gap, the more of the blade is exposed to the skin, hence the greater risk of nicks and cuts for an inexperienced user. However, experienced shavers often prefer a larger blade exposure for the greater control it affords over the angle of the blade as it meets the skin.
As far as weight is concerned, the heavier the razor, the more aggressive it is generally perceived to be. Weight balance (such as whether a razor is more head-heavy or handle-heavy) also plays a role, with razors balanced more toward the head often considered milder shavers than their handle-heavy brethren.
A simple way to estimate the aggressiveness of two fixed-head (non-adjustable) razors is to compare their respective blade gap and weight.
Again: there are factors other than the blade gap size that might make a razor seem more or less aggressive. Most notable is "blade exposure", or, the protrusion of the blade above a line tangent to the razor head and blade guard as they touch the face (see picture for more information and terminology).
Aggressiveness and ExposureAggressiveness of a safety razor can be thought of as the degree to which a blade is exposed to the face and beard, or conversely the degree to which the face and beard are not protected from the blade by the razor's safety features.
The two things that protect your face and beard from the blade are the razor's cap and the razor's guard. The cap and guard touch the skin while shaving and the blade is exposed to the skin between the two. Thus, the blade exposure can be described as the distance the blade protrudes past an imaginary tangent between cap and guard. The "gap" discussed above is not the same as the exposure as defined here, but larger gaps will tend to create larger exposures (and make it more possible for the skin to be caught inside the gap), given that the rest of the geometry stays about the same. So, the above measurements give an approximate ranking.
Another factor in aggressiveness might be the angle that the blade makes with that imaginary line. There is probably an ideal angle, usually stated as around 30 degrees from the face, but that might be different for different beards and maybe even different for different areas of the same beard.
One advantage of an aggressive razor may be that the user has more control over the angle at which the blade touches the skin.